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Alteration and abnormal epigenetic mechanisms can lead to the aberration of normal biological functions and the occurrence of several diseases. The histone deacetylase (HDAC) family of enzymes is one of the prime regulators of epigenetic functions modifying the histone proteins, and thus, regulating epigenetics directly. HDAC1 is one of those HDACs which have important contributions to cellular epigenetics. The abnormality of HDAC is correlated to the occurrence, progression, and poor prognosis in several disease conditions namely neurodegenerative disorders, cancer cell proliferation, metastasis, chemotherapy resistance, and survival in various cancers. Therefore, the progress of potent and effective HDAC1 inhibitors is one of the prime approaches to combat such diseases. In this study, both regression and classification-based molecular modelling studies were conducted on some AR-42 derivatives as HDAC1 inhibitors to elucidate the crucial structural aspects that are responsible for regulating their biological responses. This study revealed that the molecular polarizability, van der Waals volume, the presence of aromatic rings as well as the higher number of hydrogen bond acceptors might affect prominently their inhibitory activity and might be responsible for proper fitting and interactions at the HDAC1 active site to pertain effective inhibition.

Objectives The wide spectrum of clinical outcomes to SARSCoV-2 exposure suggests that early immune responses play a pivotal role 1 We aim to describe early, longitudinal, local (nasal mucosal lining fluid) and systemic (peripheral blood) cytokine and cellular immune responses to SARS-CoV-2 in a symptomatic index case and their household contacts with detailed clinical and virological phenotyping We hypothesise that immune responses at symptom onset would correlate with outcomes Methods Participants from the London area are referred to INSTINCT study by general practitioners as suspected, or Public Health England as laboratory-confirmed, cases (ethical review details: IRAS 282820, approved 24 04 2020) Households are visited the day after identification and again on days 7, 15 and 28 Clinical and exposure questionnaires, samples of environment (surface swabs and air);oropharynx (swabs);nasal mucosa (synthetic absorptive matrix) and blood, and daily symptom diaries are collected Samples are analysed by PCR, serology, 20-plex cytokine assay and flow cytometry in institutional laboratories Results The index case was the first SARS-CoV-2 PCR-positive recruit of INSTINCT, confirmed on oropharyngeal swab 5 days after symptom onset Contacts 1 and 2, the spouse and daughter, became symptomatic 2 days after the index case and were confirmed PCR-positive 3 days after symptom onset The three PCR-positive individuals seroconverted during follow-up Contact 3, the son, remained asymptomatic, PCRand serology-negative throughout (figure 1a-b) None required hospitalisation Swabs of the kettle and fridge handles were positive for virus, while other household surfaces and air samples were negative Induction, peak and decline of interferonl-1 and IP-10 levels were captured in nasal mucosa, with lower serum levels (figures 1c-f) Conclusion These data demonstrate the ability of the INSTINCT household contact study to capture early immune responses in mild SARS-CoV-2 infection, not captured by COVID-19 hospital cohort studies Early nasal mucosal cytokine responses to SARS-CoV-2 infection are not reflected in serum The correlations observed provide cogent hypotheses that will be tested in the larger INSTINCT cohort, with implications for COVID-19 risk stratification, therapeutics, prophylaxis and vaccinology

Background: The SARS-CoV-2 Delta variant is highly transmissible and spreading globally but a detailed understanding of community transmission risks in highly vaccinated populations is lacking. Methods: Between September 2020 and August 2021, we recruited 510 community contacts of 422 UK COVID-19 cases to a cohort study. A total of 7194 upper respiratory tract (URT) samples were tested from sequential daily sampling of participants for up to 20 days. We analysed transmission risk by vaccination status for 139 contacts exposed to the Delta variant. We compared viral load (VL) trajectories from fully-vaccinated cases of Delta infection (n=19) with unvaccinated Delta (n=10), Alpha (n=39) and pre-Alpha (n=49) infections. Findings: The household secondary attack rate for fully-vaccinated contacts exposed to Delta was 19.7% (95%CI:11.6-31.3%), compared with 35.7% (95%CI:16.4-61.2%) in the unvaccinated. One third of infections in Delta-exposed contacts arose from fully-vaccinated index cases and one half of infected contacts were also fully-vaccinated. Seven transmission events between fully vaccinated index-contact pairs occurred. Genomic analysis confirmed transmission pathways between fully-vaccinated individuals within three households. Peak VL was similar in vaccinated and unvaccinated individuals with Delta variant infection but vaccinated Delta cases saw significantly faster VL decline than unvaccinated Alpha or Delta cases. Within infected individuals, faster VL growth was correlated with higher peak VL and slower decline. Interpretation: Although vaccination reduces the risk of Delta infection and causes some changes to viral kinetics, fully-vaccinated individuals with breakthrough infections have peak URT VL similar to unvaccinated cases and can efficiently transmit infection in household settings, including to fully vaccinated contacts. Funding: National Institute for Health Research (Award:NIHR200927) Declaration of Interest: The authors declare no relevant conflicts. Ethical Approval: The study was approved by the Health Research Authority (Research Ethics Committee reference: 20/NW/0231).

Cancer, the seventh most fatal disease in the world, poses a long struggle to combat this deadly disease. Economically and pharmacologically important members of Zingiberaceae plant family have helped to eradicate a number of ailments worldwide. This review highlights gingers and their wide spectrum of medicinal values focussing on their role as anticancer agents with facts and data obtained from literature review performed using PubMed, PMC, ScienceDirect, Google Scholar in a systematic way. Among the many genera underlined in this review, several species of Hedychium have emerged as potential cancer treatments with remarkable activity against different forms of tumour. However this genus is not much explored to unravel its value to medical research. Several species have been found to have cytotoxic, antiinflammatory, antioxidant and antitumour activities but not many attempts made to establish the plant principles as anticancer agents.

Vascular wilt (caused by Fusarium udum) is the most important disease of pigeonpea. Breeding strategies are needed to develop durable resistance against this pathogen. Knowledge of the genetic and pathogenic variability among isolates of F. udum is essential for effective deployment of resistance. Thirteen isolates of F. udum, collected from three regions of India were studied using cultural characteristics, molecular variability and pathogenicity. The isolates of F. udum showed variability in aerial and radial mycelium growth, colour of mycelia, substrate pigmentation, length and septation of macro- and microconidia. Amplified fragment length polymorphism (AFLP) analysis of the isolates determined seven phylogenetic groups. Pathogenesis and progress of wilt on susceptible pigeonpea cultivars varied and pathogenic isolates from the same phylogenetic group exhibited similarities in timing of infection and colonization. Non-pathogenic isolates formed separate clusters in the phylogenetic tree. The timing of fungal invasion, vascular clogging, drooping of shoots, and wilt establishment were demonstrated for the first time in pigeonpea. Vascular clogging occurred with susceptible cultivars at 78–84, 54–60, 48–60 and 36–48 h post inoculation (HPI) when inoculated with isolates of F. udum from AFLP groups 1, 3, 6 and 7, respectively. Subsequently, susceptible cultivars inoculated with isolates from the same groups exhibited wilt at 144–168, 120–144, 96–120 and 72–96 HPI, respectively. This study contributes to characterising vascular wilt of pigeonpea.

Saltwater intrusion in estuaries is expected to become a more serious issue around the world due to climate change. Van der Burgh's coefficient, K, is a good proxy for describing the relative contribution of the tide-driven and gravitational components of salt transport in estuaries. However, debate continues over the use of K value for an estuary where K should be constant or spatially varying or a time-independent factor for different river discharge conditions. In addition, whether K functions in an inverse salinity gradient area of a salt plug estuary has not been examined thus far. In this study, we determined K during spring and neap tides in the dry (750 m−3 s−1) seasons in a salt plug estuary with an exponentially varying width and depth to examine the relative contributions of tidal versus density-driven salt transport mechanisms. High-resolution salinity data were used to determine K. Gravitational circulation (K~0.8) was entirely dominant over tidal dispersion during spring and neap tides in the wet season such that salt transport upstream was effectively reduced, resulting in the estuary remaining in a relatively fresh state. In contrast, during the dry season, K increases gradually seaward and landward (K~0.74) from the salt plug area (K~0.65), similar to an inverse and positive estuary, respectively. As a result, density-induced inverse gravitational circulation between the salt plug and the sea facilitates inverse estuarine circulation. On the other hand, positive estuarine circulation between the salt plug and the river area arose due to density-induced positive gravitational circulation induced by the tide during the dry season, causing the intrusion of high-salinity bottom water upstream. Our results explicitly show that K varies spatially and depends on the river discharge. This result provides a better understanding of the distribution of hydrographic properties as well as the distributions of pollutants, nutrients and biota within large estuaries.

The nonlinear propagation of dust–ion acoustic (DIA) waves in an obliquely propagating magnetized dusty plasma, consisting of bi-maxwellian electrons (namely lower and higher temperature maxwellian electrons), negatively charged immobile dust grains, and inertial ions is rigorously investigated by deriving the Zakharov–Kuznetsov equation. Later, the multidimensional instability of the DIA solitary waves (DIASWs) is analyzed using the small-k perturbation technique. It is investigated that the nature of the DIASWs, the instability criterion, and the growth rate of the perturbation mode are significantly modified by the external magnetic field and the propagation directions of both the nonlinear waves and their perturbation modes. The implications of the results obtained from this investigation in space and laboratory dusty plasmas are briefly discussed.

A rigorous theoretical investigation has been made on multi-dimensional instability of obliquely propagating electrostatic dust-ion-acoustic (DIA) solitary structures in a magnetized dusty electronegative plasma which consists of Boltzmann electrons, nonthermal negative ions, cold mobile positive ions, and arbitrarily charged stationary dust. The Zakharov-Kuznetsov (ZK) equation is derived by the reductive perturbation method, and its solitary wave solution is analyzed for the study of the DIA solitary structures, which are found to exist in such a dusty plasma. The multi-dimensional instability of these solitary structures is also studied by the small-k (long wave-length plane wave) perturbation expansion technique. The combined effects of the external magnetic field, obliqueness, and nonthermal distribution of negative ions, which are found to significantly modify the basic properties of small but finite-amplitude DIA solitary waves, are examined. The external magnetic field and the propagation directions of both the nonlinear waves and their perturbation modes are found to play a very important role in changing the instability criterion and the growth rate of the unstable DIA solitary waves. The basic features (viz. speed, amplitude, width, instability, etc.) and the underlying physics of the DIA solitary waves, which are relevant to many astrophysical situations (especially, auroral plasma, Saturn’s E-ring and F-ring, Halley’s comet, etc.) and laboratory dusty plasma situations, are briefly discussed.

Introduction : Composite resins have become one of the most commonly used direct restorative materials for anterior and posterior teeth. Objectives : To observe and analyze the gap at the resin dentin interface in class II cavities restored with light cure composite resin in four experimental groups employing 37% phosphoric acid or self etching monomers and restored with /without light cure flowable composite resin. Methods: 40 sound maxillary first premolars, extracted due to orthodontic reasons was taken, distoproximal cavities were prepared and divided into 4 groups. Teeth of Group 1 was etched by 37% Phosphoric acid and light cure flowable composite resin was used, in group 2 ,two coats of self etching acidic monomer were applied and light cure flowable composite resin was used. Teeth of group 3 was etched with 37% phosphoric acid and restored without light cure flowable composite resin and in group 4, two coats of self etching acidic monomer were applied and restored without using light cure flowable composite resin material. Thermocycling was done after finishing and polishing and viewed under scanning electron microscope to observe and analyze the gap between tooth and the restoration. Result: Gap was observed at dentin-composite resin interface in all 4 groups. Results were evaluated by F-test and Manwhitney U test. No statistically significant difference was found. Conclusion: Use of flowable composite resin liner and the etching technique do not have any influence on the gap. DOI: http://dx.doi.org/10.3126/hren.v10i2.6571 Health Renaissance 2012; Vol 10 (No.2); 98-104

We demonstrate the distinct glassy transport phenomena associated with the phase separated and spin-glass-like phases of La0.85Sr0.15CoO3, prepared under different heat-treatment conditions. The low-temperature annealed (phase-separated) sample, exhibits a small change in resistance, with evolution of time, as compared to the high-temperature annealed (spin glass) one. However, the resistance change as a function of time, in both cases, is well described by a stretched exponential fit, signifying the slow dynamics. Moreover, the ultraviolet spectroscopy study evidences a relatively higher density of states in the vicinity of EF for low-temperature annealed sample and this correctly points to its less semiconducting behavior.

The dust-ion-acoustic solitary waves (DIA SWs) in an unmagnetized dusty plasma containing non-thermal electrons, cold mobile positive ions, and stationary arbitrarily (positively and negatively) charged static dust have been theoretically studied. The reductive perturbation technique has been employed to derive the Korteweg-de Vries equation, which admits SW solutions under certain conditions. It has been also shown that the basic features (amplitude, width, speed, etc.) of DIA SWs are significantly modified by the polarity of dust and non-thermal electrons. The implications of our results in space and laboratory dusty plasma situations are briefly discussed.

We present a comparative study of the near fermi-level electronic structure of single crystal and highly oriented pyrolytic graphite (HOPG). Angle resolved photoelectron spectroscopy and angle resolved inverse photoelectron spectroscopy have been used to probe the occupied and unoccupied electronic states, respectively. The band dispersions showed by single crystal graphite along its Γ K and Γ M symmetry directions were found to be in agreement with calculated band structure of graphite. The π bands of single crystal graphite were found to have a splitting of ∼ 0.5 eV at the K-point. We also observe the presence of a quasiparticle peak below EF at the K point at low temperature which indicates a strong electron–phonon coupling in graphite. In HOPG, the M and K points like features were found to be present in the same radial direction due to the superposition of the Γ M and Γ K directions. Results from our angle resolved inverse photoemission spectroscopy present the dispersion of the conduction band states, particularly the lower π ⁎ band. We have also found the presence of some non-dispersive features in both the valence and the conduction bands.

The nucleosome, which is composed of DNA wrapped around a histone octamer, is a fundamental unit of chromatin and is duplicated during the eukaryotic DNA replication process. The evolutionarily conserved histone chaperone cell cycle gene 1 (CCG1) interacting factor A/anti-silencing function 1 (CIA/Asf1) is involved in histone transfer and nucleosome reassembly during DNA replication. CIA/Asf1 has been reported to split the histone (H3–H4)2 tetramer into histone H3–H4 dimer(s) in vitro, raising a possibility that, in DNA replication, CIA/Asf1 is involved in nucleosome disassembly and the promotion of semi-conservative histone H3–H4 dimer deposition onto each daughter strand in vivo. Despite numerous studies on the functional roles of CIA/Asf1, its mechanistic role(s) remains elusive because of lack of biochemical analyses. The biochemical studies described here show that a V94R CIA/Asf1 mutant, which lacks histone (H3–H4)2 tetramer splitting activity, does not form efficiently a quaternary complex with histones H3–H4 and the minichromosome maintenance 2 (Mcm2) subunit of the Mcm2-7 replicative DNA helicase. Interestingly, the mutant enhances nascent DNA strand synthesis in a cell-free chromosomal DNA replication system using Xenopus egg extracts. These results suggest that CIA/Asf1 in the CIA/Asf1–H3–H4–Mcm2 complex, which is considered to be an intermediate in histone transfer during DNA replication, negatively regulates the progression of the replication fork.

The early solar observations of Covington (1947) established a good relation between 10.7 cm solar flux and the presence of sunspots on solar disk. The first spatially resolved observation with a two-element interferometer at arc min resolution by Kundu (1959) found that the radio source at 3 cm has a core-halo structure; the core is highly polarized and corresponds to the umbra of a sunspot with magnetic fields of several hundred gauss, and the halo corresponds to the diffuse penumbra or plage region. The coronal temperature of the core was interpreted as due to gyroresonance opacity produced by acceleration of electrons gyrating in a magnetic field. Since the opacity is produced at resonant layers where the frequency matches harmonics of the gyrofrequency, the radio observation could be utilized to measure the coronal magnetic field. Since this simple interferometric observation, the next step for solar astronomers was to use arc second resolution offered by large arrays at cm wavelengths such as Westerbrock Synthesis Radio Telescope and the Very Large Array, which were primarily built for cosmic radio research. Currently, the Owens Valley Solar Array operating in the range 1-18 GHz and the Nobeyama Radio Heliograph at 17 and 34 GHz are the only solar dedicated radio telescopes. Using these telescopes at multiple wavelengths it is now possible to explore three dimensional structure of sunspot associated radio sources and therefore of coronal magnetic fields. We shall present these measurements at wavelengths ranging from 1.7 cm to 90 cm and associated theoretical developments.

Mcm2–7 is recruited to eukaryotic origins of DNA replication by origin recognition complex, Cdc6 and Cdt1 thereby licensing the origins. Cdc6 is essential for origin licensing during DNA replication and is readily destabilized from chromatin after Mcm2–7 loading. Here, we show that after origin licensing, deregulation of Cdc6 suppresses DNA replication in Xenopus egg extracts without the involvement of ATM/ATR-dependent checkpoint pathways. DNA replication is arrested specifically after chromatin binding of Cdc7, but before Cdk2-dependent pathways and deregulating Cdc6 after this step does not impair activation of origin firing or elongation. Detailed analyses revealed that Cdc6 deregulation leads to strong suppression of Cdc7-mediated hyperphosphorylation of Mcm4 and subsequent chromatin loading of Cdc45, Sld5 and DNA polymerase α. Mcm2 phosphorylation is also repressed although to a lesser extent. Remarkably, Cdc6 itself does not directly inhibit Cdc7 kinase activity towards Mcm2–4–6–7 in purified systems, rather modulates Mcm2–7 phosphorylation on chromatin context. Taken together, we propose that Cdc6 on chromatin acts as a modulator of Cdc7-mediated phosphorylation of Mcm2–7, and thus destabilization of Cdc6 from chromatin after licensing is a key event ensuring proper transition to the initiation of DNA replication.

We have studied the occupied and unoccupied electron states of the Pr 1 - x Ca x MnO 3 ( x = 0.2 , 0.33 and 0.4) near the Fermi level across their ferromagnetic–antiferromagnetic phase boundary using ultraviolet photoemission spectroscopy and inverse photoemission spectroscopy. The photoemission data show that the pseudogap formation in these compounds occur over an energy scale of 0.48 ± 0.02 eV . From a combined analysis of the photoemission and inverse photoemission results, we have estimated the charge transfer energy in these compounds to be ∼ 2.8 ± 0.2 eV . The results have been explained on the basis of the theoretical models that describe the electronic phase separation.

A preliminary checklist of Tamaricaceae in the Indian subcontinent has been prepared on the basis of primary observations of different taxa belonging to this family in wild habitats and on secondary observations based on examining herbarium specimens and taxonomic literature. On the Indian subcontinent (comprising Bangladesh, Bhutan, Myanmar, Nepal, Pakistan, Sri Lanka and India), the family Tamaricaceae is poorly represented (20% of all species). The present paper deals with a brief review of distribution, endemism, possible fossil ancestry, economic potential and survival threat on existing taxa, etc. The present status of endemism of Tamaricaceae in Indian subcontinent (22.5% in 2002–2007) has been compared to the data of previous investigations (50% in 1939–1940) done in nineteenth century. The decreasing rate of endemism either indicates decreasing number of endemic taxa or increasing span of distribution of pan-endemic taxa belonging to this family. For better understanding of the functional aspects...

In networks carrying large volume of traffic, accurate traffic characterization is necessary for understanding the dynamics and patterns of network resource usage. Previous approaches to flow characterization are based on random sampling of the packets (e.g., Cisco's NetFlow) or inferring characteristics solely based on long lived flows (LLFs) or on lossy data structures (e.g., bloom filters, hash tables). However, none of these approaches takes into account the heavy-tailed nature of the Internet traffic and separates the estimation algorithm from the flow measurement architecture.In this paper, we propose an alternate approach to traffic characterization by closely linking the flow measurement architecture with the estimation algorithm. Our measurement framework stores complete information related to short lived flows (SLFs) while collecting partial information related to LLFs. For real-time separation of LLFs and SLFs, we propose a novel algorithm based on typical sequences from information theory. The distribution (pdf) and sample space of the underlying traffic is estimated using the non-parametric Parzen window technique and likelihood function defined over the Coupon collector problem. We validate the accuracy and performance of our estimation technique using traffic traces from the internal LAN in our laboratory and from National Library for Applied Network Research (NLANR).

Although initiation of DNA replication is considered to be highly coordinated through multiple protein–DNA and protein–protein interactions, it is poorly understood how particular locations within the eukaryotic chromosome are selected as origins of DNA replication. Here, we discuss recent reports that present structural information on the interaction characteristics of the archaeal orthologues of the eukaryotic origin recognition complex with their cognate binding sequences.1,2 Since the archaeal replication system is postulated as a simplified version of the one in eukaryotes, by analogy, these works provide insights into the functions of the eukaryotic initiator proteins. BioEssays 30:208–211, 2008. © 2008 Wiley Periodicals, Inc.

Observations of a solar flare at 617 MHz with the Giant Meter-wave Radio Telescope (GMRT) are used to study the morphology of flare radio emission at decimetric wavelengths. There has been very little imaging in the 500 – 1000 MHz frequency range, but it is of great interest, since it corresponds to densities at which energy is believed to be released in solar flares. This event has a very distinctive morphology at 617 MHz: the radio emission is clearly resolved by the 30″ beam into arc-shaped sources seeming to lie at the tops of long loops, anchored at one end in the active region in which the flare occurs, with the other end lying some 200 000 km away in a region of quiet solar atmosphere. Microwave images show fairly conventional behaviour for the flare in the active region: it consists of two compact sources overlying regions of opposite magnetic polarity in the photosphere. The decimetric emission is confined to the period leading up to the impulsive phase of the flare, and does not extend over a wide frequency range. This fact suggests a flare mechanism in which the magnetic field at considerable height in the corona is destabilized a few minutes prior to the main energy release lower in the corona. The radio morphology also suggests that the radiating electrons are trapped near the tops of magnetic loops, and therefore may have pitch angles near 90˚.

We describe a flare of GOES class M5.7 that was observed simultaneously by RHESSI (Ramaty High Energy Solar Spectroscopic Imager) and NoRH (Nobeyama Radio Heliograph). The flare occurred in AR 9866 located near the disk center. The hard X-ray (HXR), microwave, EIT, and TRACE 195 A observations indicate that the flaring region consisted of a complex of multiple loops. In the microwave domain the source morphology, the timing, the polarization characteristics, and the photospheric magnetic fields clearly indicate that it is of a class characterized as a "double loop" configuration, meaning two systems of magnetic flux, each consisting of many smaller loops. The observations suggest the existence of a small loop system created by the emergence of new flux, which interacts with an old flux system, and of a remote flare site that is observed primarily in radio. The former is the main flare site where we observe microwave, HXR, and EUV emissions. In HXR there are two main identifiable loop systems. The first is an elongated one filled with energetic electrons primarily emitting lower energy (12-25 keV) HXR with a colocated microwave source; this source has distinct footpoints at higher X-ray energies. The second loop system is implied by compact HXR sources in opposite magnetic polarities separated by a distance greater than the length of the first loop system. Spectroscopic analysis of the RHESSI data shows that the spectrum can be fitted with a thick-target model with a thermal component and a broken power-law component of the electron energy distribution. This model is used to address the thermal/nonthermal and radio/HXR electron number problems.

Aims. We present a summary of the analysis of thirty microflares, observed simultaneously by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) in hard X-rays and by Nobeyama RadioHeliograph (NoRH) in microwaves (17 GHz). Methods. We used microflares observed by RHESSI in the energy range 3-25 keV, and for larger events, up to 35 keV. The observations were made 2002, May 2-6. Results. We describe the imaging characteristics of these microflares including their locations in hard X-rays and microwaves and the relative positions of the micro-flaring sources. We discuss the brightness temperatures, emission measures and their hard X-ray spectral properties. We see small (mini) flaring loops clearly in NoRH and RHESSI images. The microwave emission often seems to come from the RHESSI foot points (for higher energies), and from the entire small (mini) flaring loop (for lower energies). Sometimes the two (microwave and hard X-ray) sources coincide, at other times they are at opposite ends of a mini flaring loop. Typically, the hard X-ray spectrum of the microwave associated RHESSI microflares can be fit by an isothermal component at low energies (below 10 or 12 keV) and a nonthermal component at higher energies (above 12 keV). Conclusions. Microflares in hard X-rays and in microwaves behave like normal flares in many respects. They can have both thermal and nonthermal components appearing in bremsstrahlung and gyrosynchrotron radiation.

We consider manifestations of accelerated electrons in microwave and hard X-ray emissions from solar flares. To meet our objectives, we discuss two events — those of 1999 March 16 and February 16. The first event is a short-duration burst, while the second is a long-duration event. An analysis of the first event leads to the conclusion that: 1) a seemingly single-loop configuration can actually be a double-loop one, and 2) it is possible that the pitch-angle distribution of the radio-emitting electrons can be anisotropic with practically no non-zero pitch angles. The second event shows seemingly intersecting flaring loops, and the formation of a post-eruptive arcade that can proceed as a series of double-loop interactions. From these and other published results, we conclude that: 1) doubleloop configurations can be responsible for flares showing diverse morphologies and time profiles; 2) the pitch-angle distribution of accelerated electrons can be strongly anisotropic, with an excess of small angles, contributing to a rather narrow energy range of the microwave-emitting electrons.

The members of the family Theaceae are distributed in tropical and subtropical regions, in America and Asia, a few in Africa. In Indian subcontinent (comprising of Bangladesh, Bhutan, Myanmar, Nepal, Pakistan, Sri Lanka and India), it is well-represented (50% of the total taxa). The present paper deals with distribution, phytoendemism, possible fossil ancestry, potential survival threat on existing taxa etc. of Theaceae in Indian subcontinent.

International audience; We present an analysis of five microflares, three observed simultaneously by RHESSI in hard X-rays and Nobeyama RadioHeliograph (NoRH) in microwaves (17 GHz) and two observed by RHESSI and Nancay RadioHeliograph (NRH) at metric wavelengths (150-450 MHz). Since we have no radio imaging telescopes simultaneously operating at microwave and meter wavelengths in the same time zone, we are obliged to use a different set of metric events in contrast to that used for comparison with the two radio wavelengths. We are interested in using the locations and other imaging characteristics of the events from both RHESSI and radio observations instead of just temporal correlation. So we have used the Nancay (France) metric radioheliograph at 150-450 MHz for this purpose. Here we describe the properties of five events - three in microwaves and two at metric wavelengths. We discuss the brightness temperatures, emission measures and the hard X-ray spectral properties of these microevents. One sees small (mini) flaring loops clearly in NoRH and RHESSI images. The microwave emission often seems to come from the RHESSI foot points (for higher energies), and from the entire small (mini) flaring loop (for lower energies).The RHESSI microflares seem to be associated in position with metric type III bursts. Frequently, the hard X-ray spectrum of the microwave associated RHESSI microflares can be fit by a thermal component at low energies (˜3-12 keV) and a nonthermal component at higher energies (˜12-20 keV).

We describe two flares of GOES class M5.7 and 1.5 which were observed simultaneously by RHESSI (Ramaty High Energy Solar Spectroscopic Imager) and NoRH (Nobeyama Radio Heliograph). Both flares exhibit slow motions suggestive of changing magnetic shear, loop expansion, or gradual reconnection. One flare is clearly a coronal hard X-ray and microwave flare.

We present the long term variation of solar corona based on SOHO/EIT observations from 1996 to 2004. EIT provides diagnostics of bulk corona in three channels with overlapping temperature range from 0.5 MK to 2.7 MK and with high spatial resolution. We find that the coronal emission measure increases by a factor of 4 from $2.0\times10^{27}$ cm $^{-5}$ at the solar minimum to $8.0\times10^{27}$ cm $^{-5}$ at the solar maximum. In the meantime, the overall temperature of the corona increases from 1.3 MK to 1.7 MK To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We discuss a filament eruption/coronal mass ejection (CME) event associated with a flare of GOES class M2.8 that occurred on 2001 November 17. This event was observed by the Nobeyama Radio Heliograph (NoRH) at 17 and 34 GHz. NoRH observed the filament during its eruption both as a dark feature against the solar disk and a bright feature above the solar limb. The high cadence of the radio data allows us to follow the motion of the filament at high time resolution to a height of more than half a solar radius. The filament eruption shows a very gradual onset and then a rapid acceleration phase coincident with the launch of a fast halo CME. Soft X-ray and extreme-ultraviolet (EUV) images show heating in a long loop underneath the filament prior to the flare. The NoRH height-time plot of the filament shows a roughly constant gradual acceleration for 1 hr, followed by a very abrupt acceleration coincident with the impulsive phase of the associated flare, and then a phase of constant velocity or much slower acceleration. This pattern is identical to that recently found to occur in the motion of flare-associated CMEs, which also show a sharp acceleration phase closely tied to the impulsive phase of the flare. When the rapid acceleration occurs in this event, the flare site and the filament are separated by ~0.5 R☉, making it unlikely that a disturbance propagates from one location to the other. Models in which a disruption of the large-scale coronal magnetic field simultaneously permits the acceleration of the filament and the flare energy release seem to be a better explanation for this event.

We present an overview of the radio observations of the X1.5 flare of 2002 April 21 and complementary data from other wavelengths. This flare was fairly well observed by the Ramaty High Energy Spectroscopic Imager (RHESSI) spacecraft and fully observed by the Nobeyama Radioheliograph (NoRH) at 17 and 34 GHz. This long-duration event lasted more than 2 hr and featured a beautiful arcade of rising loops on the limb visible at X-ray, EUV, and radio wavelengths. The main flare was preceded by a small event 90 minutes earlier showing a long EUV loop connecting well-separated radio and hard X-ray sources. The main flare itself starts with a compact radio and hard X-ray source at the eastern end of the region that develops into emission close to the solar surface (and well inside the solar limb) over a large region to the northwest. As the flare proceeds, a large set of loops is seen to rise well above the solar limb. Distinct regions of radio emission with very different time behavior can be identified in the radio images, and, in particular, a peculiar nonthermal source seen in radio and hard X-rays low in the corona at the base of the arcade is seen to turn on 30 minutes after the start of the impulsive phase. At about the same time, an extremely intense burst of coherent radio emission is seen from 500 to 2000 MHz; we speculate that this lower-frequency burst is produced by electrons that are accelerated in the nonthermal source at the base of the arcade and injected into the loop system where they radiate plasma emission in the 1010 cm-3 density plasma at the top of the arcade of loops. This event is striking as a demonstration of the many ways in which a flare can produce radio emission, and the combined data at different wavelengths reveal a diversity of energy release and nonthermal acceleration sites.

We present the first observations of a solar flare with the GMRT. An M2.8 flare observed at 1060 MHz with the GMRT on Nov 17 2001 was associated with a prominence eruption observed at 17 GHz by the Nobeyama radioheliograph and the initiation of a fast partial halo CME observed with the LASCO C2 coronograph. Towards the start of the eruption, we find evidence for reconnection above the prominence. Subsequently, we find evidence for rapid growth of a vertical current sheet below the erupting arcade, which is accompanied by the flare and prominence eruption., Accepted for publication in Solar Physics

We present the first comparison between radio images of high-energy electrons accelerated by a solar flare and images of hard X-rays produced by the same electrons at photon energies above 100 keV. The images indicate that the high-energy X-rays originate at the footpoints of the loops dominating the radio emission. The radio and hard X-ray light curves match each other well and are quantitatively consistent with an origin in a single population of nonthermal electrons with a power-law index of around 4.5-5. The high-frequency radio spectral index suggests a flatter energy spectrum, but this is ruled out by the X-ray spectrum up to 8 MeV.

We report the multiwavelength investigations of an eruptive flare event that occurred on 2001 April 2 at about 11 UT. The manifestations associated with this flare event have been studied from the near-Sun region to about 0.5 AU. The H-alpha images from the Meudon Spectroheliograph reveal a fast spectacular eruption of plasmoids from the flare site to the west and a Moreton wave disturbance propagating toward the south, A bright, fast, wide coronal mass ejection (CME) associated with this eruptive event was imaged by SOHO/LASCO and the remote-sensing interplanetary scintillation technique. The timings and positions of the Type II radio bursts, H-alpha eruption, and CME onset as well as the magnetic field configuration suggest a release of energy at the null point. The results seem to support the "breakout" scenario proposed by Antiochos and coworkers, and they are also suggestive that the energy release is followed by magnetic reconnection between the low-lying loops near the separatrix and the loop system above them.

We studied a microwave burst that showed deep quasi-periodic pulsations using imaging observations at 17 and 34 GHz. Strongly modulated pul sations appear in radio images from the eastern end of a long loop an d in hard X-rays from the western end of the loop. Radio modulations are seen at the western end of the loop but at a level some 20 times weaker than at the eastern end; these radio modulations at the western end of the loop, like the hard X-ray modulations at the same locatio n, appear to lead the modulations at the eastern end by about 0.5 s, but all have the same period. The period of the modulation can be exp lained by MHD oscillations of the loop approximately 120" long connecting the sources.

We discuss a class of microwave flares whose source regions exhibit a distinctive spatial configuration; the primaryenergy release in these flares results from the interaction between emerging magnetic flux and an existing overlying region. Such events typically exhibit radio, X-ray and EUV emission at the main flare site (the site of interaction) and in addition radio emission at a remote site up to 1 × 10 5 km away in another active region. We have identified and studied more than a dozen microwave flares in this class, in order to arrive at some general conclusions on reconnection and energy release in such solar flares. Typically, these flares show a gradual rise showing many subsidiary peaks in both radio and hard X-ray light curves with a quasi-oscillatory nature with periods of 5–6 seconds, a bright compact X-ray & EUV emitting loop in the main flare source, a delay of the radio emission from the remote source relative to the main X-ray-emitting source. The magnetic field in the main flare site changes sharply at the time of the flare, and the remote site appears to be magnetically connected to the main flare site.

Dynamic logic is increasingly becoming a logic type of choice for designs requiring high speed and low area. Charge sharing is one of many problems that may cause failure in dynamic logic circuits due to their low noise immunity. The authors address the charge-sharing noise issue. Specifically, they develop an accurate but tractable model for analyzing charge sharing that avoids costly Hspice simulations. The model is used to generate test vectors using a generalized ATPG tool. The charge-sharing model and the corresponding tests are validated using Hspice simulations on industrial circuits and it is also demonstrated that test vectors that establish high amounts of charge sharing could be generated for most domino gates.

We use high-resolution radio observations to study the physical parameters of a flaring loop. The loop is visible at radio wavelengths because of gyrosynchrotron emission by nonthermal electrons (energies typically above several hundred keV) accelerated by the flare. We are able to measure the loop thickness and length with a precision on the order of 1''. We find that the loop length increases from about 60'' initially to about 80'' in the decay phase of the event. The loop (averaged along its length) initially is no more than 3'' wide. The soft and hard X-ray data obtained with the Soft X-Ray Telescope and Hard X-Ray Telescope on the Yohkoh satellite are consistent with the same loop as observed at radio wavelengths (although the soft X-ray morphology has some small differences early in the event). This event was accompanied by a coronal mass ejection and a coronal dimming visible in Solar and Heliospheric Observatory Extreme-Ultraviolet Imaging Telescope images, so it involved a very large volume of the corona, yet the radio observations clearly indicate that much of the energy release in the low corona was restricted to a region apparently no more than 2000 km across. As the event proceeds, the loop develops a bright feature at the loop top in both the radio and soft X-ray images that cannot be reproduced in gyrosynchrotron loop models in which the electron distribution has relaxed by pitch angle scattering to fill the loop. This prevents us from using the flare properties to measure the magnetic field strength and variation along the loop. The bright loop-top source may require that trapping of electrons take place at the loop top late in the event.

Closed-form expressions for the input impedance of half-wavelength rectangular microstrip antennas fed by a coaxial line at any point on any one of the nonradiating edges and open-circuited at the ends are derived. Good agreement between computed and measured data is obtained. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 28–31, 2002; DOI 10.1002/mop.10221

In this paper we discuss some recent observations of radio emission produced by high energy electrons resulting from solar flares. We discuss the spatial structure of simple weak spiky burst emissions observed simultaneously, at 17 and 34 GHz with the Nobeyama Radio Heliograph (NoRH). Using simultaneous imaging observations obtained by Yohkoh/HXT and SXT along with NoRH17 & 34 GHz observations, we attempt to model a relatively stronger and longer flare using gyrosynchrotron mechanism for the flaring radio emission.

We have studied the Mn 2p, Ca 2p, and Pr 4d core levels of Pr1–xCaxMnO3 (x = 0.2, 0.33, 0.4 and 0.84) as a function of x using X-ray photoelectron spectroscopy both at room temperature as well as 77 K. Suppression of chemical potential shifts have been observed at 77 K compared to that of room temperature spectra. We have discussed this result by considering the concept of phase separation.

The valence band electronic structure of the Bi1−xPbxFeO3 (x=0.02–0.15) system which undergoes a R3c to cubic phase transition with Pb doping has been studied by using X-ray and ultra-violet photoelectron spectroscopy. The cubic composition showed an enhancement of the oxygen 2p character in the near Fermi level density of states, possibly due to the weakening of the Fe 3d–O 2p–Bi 6p hybridization strengths following the changes in the topology of the oxygen octahedra in its structure. The compositions with the R3c structure showed a much larger band gap and band width compared to those reported from LSDA+U calculations. We attribute this to a larger effective Coulomb interaction (Ueff).

We use extensive multiwavelength data to study a flare belonging to the interacting-loop class of events identified by Hanaoka. The class of flares is identified morphologically from the presence of two well-separated radio sources in 17 GHz images (in this event, 160'' apart), with only one source showing soft X-ray emission. This event shows many of the other properties apparently shared by this class of flares: a gradual rise showing many subsidiary peaks in both radio and hard X-ray light curves with a quasi-oscillatory nature, the presence of a bright compact X-ray-emitting loop in the main flare source, a delay of the radio emission from the remote source relative to the main X-ray-emitting source, higher circular polarization in the radio emission of the remote source than in the main source, and stronger photospheric magnetic field in the remote source. The new results of our analysis are that we are able to show, using a sequence of magnetograms, that the magnetic field in the main flare site changes sharply at the time of the flare, and further we argue that the remote site is magnetically connected to the main flare site only up to the time of the main impulsive phase, at which point we believe the magnetic connection to the remote site was broken and further flare manifestations are largely confined to the main flare site. This severing of the magnetic connection between two well-separated active regions may be an intrinsic part of the energy release in this flare. The region around the main flare site also exhibits rotation in the magnetogram in the period leading up to the flare. Radio and hard X-ray oscillations with periods of order 5-10 s are observed in the rise phase of this event. If they are due to transverse oscillations of the flare loop at the Alfven speed, then the density in the loop is inferred to be of order 1011 cm-3 and to increase with time as expected.

The Sun's corona, which is composed of plasma at a temperature of a few millions of degrees, can be best viewed in two electromagnetic domains, one from wavelengths of a few angstroms to hundreds of angstroms (in the soft X-ray and EUV domain), the other from wavelengths of a few centimeters to several tens of centimeters (in the radio domain). In this paper, we present a quantitative comparison of coronal observations made in these two domains with high spatial resolution over the full disk of the Sun. The EUV observations were taken with the EIT (Extreme-Ultraviolet Imaging Telescope) on board SOHO (Solar and Heliospheric Observatory), and the radio observations were taken with the VLA (Very Large Array). The two sets of images show very similar morphologies, indicating that the different wavelengths originate from common solar features. We predict radio fluxes using the temperature and emission measure of the corona calculated from EIT observations, adopting Meyer's table of coronal abundances for the calculations. In each of the seven observations investigated, there always exists a good linear correlation in the pixel-by-pixel correlation plot between the predicted and the observed radio flux for coronal features over a wide range of flux variation. Nevertheless, the predicted radio flux is systematically larger than that observed by a factor of 2.0 ± 0.2, on average. We attribute the difference to the underestimation of the abundance of Fe relative to H in the abundances adopted by Meyer. On this basis, we place the absolute Fe abundance in the corona at 7.8 × 10-5, which has an enrichment factor of 2.4 relative to the accepted photospheric Fe abundance.

In this paper we report the first detection of metric/decimetric radio emission associated with two soft X-ray plasmoid ejecta events that occurred during two limb flares observed by the Yohkoh SXT. In the first event a loop started to rise slowly (~10 km s-1) before the beginning of the hard X-ray impulsive phase of the flare. At about the onset of the impulsive flare, there was acceleration of the ejecta, resulting in a speed of 130 km s-1 and finally to ~200 km s-1. The associated radio emission was observed with the Nancay radioheliograph (NRH) in the frequency range of 230-450 MHz. It was an unpolarized continuum that lasted 8-10 minutes. The 410 MHz source was located close to the height where the plasmoid was last identified in the SXT images. In the second event an eruption resulted in the expansion of a large-scale, looplike feature and the development of two plasmoid ejecta which moved in different directions. The speed of the ejecta was 60-100 km s-1. In this event, the associated radio emission was a long-lasting (about 2 hr) continuum observed from 450 to 164 MHz. The onset of the low-frequency emission was delayed with respect to the onset of the high-frequency emission. In both cases the radio sources were located above the soft X-ray ejecta in the general direction of the prolongation of the ejecta movement. In both cases the radio emission comes from nonthermal electrons which are accelerated in close relationship with the propagation of the X-ray plasmoid: as the plasmoid reaches higher altitudes, it interacts with increasingly more extended magnetic field lines and new coronal sites of production of nonthermal electrons are created.

The temporal relationship between coronal mass ejections (CMEs) and associated solar flares is of great importance to understanding the origin of CMEs, but it has been difficult to study owing to the nature of CME detection. In this paper, we investigate this issue using the Large Angle and Spectrometric Coronagraph and the EUV Imaging Telescope observations combined with GOES soft X-ray observations. We present four well-observed events whose source regions are close to the limb such that we are able to directly measure the CMEs' initial evolution in the low corona (~ 1-3 R☉) without any extrapolation; this height range was not available in previous space-based coronagraph observations. The velocity-time profiles show that kinematic evolution of three of the four CMEs can be described in a three-phase scenario: the initiation phase, impulsive acceleration phase, and propagation phase. The initiation phase is characterized by a slow ascension with a speed less than 80 km s-1 for a period of tens of minutes. The initiation phase always occurs before the onset of the associated flare. Following the initiation phase, the CMEs display an impulsive acceleration phase that coincides very well with the flares' rise phase lasting for a few to tens of minutes. The acceleration of CMEs ceases near the peak time of the soft X-ray flares. The CMEs then undergo a propagation phase, which is characterized by a constant speed or slowly decreasing in speed. The acceleration rates in the impulsive acceleration phase are in the range of 100-500 m s-2. One CME (on 1997 November 6, associated with an X9.4 flare) does not show an initiation phase. It has an extremely large acceleration rate of 7300 m s-2. The possible causes of CME initiation and acceleration in connection with flares are explored.