bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grand minima of solar activity during the last millennia
Authors: Usoskin Ilya G. , Solanki Sami K. , Kovaltsov Gennady A. 
Published: July 2012

AbstractIn this review we discuss the occurrence and statistical properties of Grand minima based on the available data covering the last millennia. In particular, we consider the historical record of sunspot numbers covering the last 400 years as well as records of cosmogenic isotopes in natural terrestrial archives, used to reconstruct solar activity for up to the last 11.5 millennia, i.e. throughout the Holocene. Using a reconstruction of solar activity from cosmogenic isotope data, we analyze statistics of the occurrence of Grand minima. We find that: the Sun spends about most of the time at moderate activity, 1/6 in a Grand minimum and some time also in a Grand maximum state; Occurrence of Grand minima is not a result of long-term cyclic variations but is defined by stochastic/chaotic processes; There is a tendency for Grand minima to cluster with the recurrence rate of roughly 2000-3000 years, with a weak ≈210-yr periodicity existing within the clusters. Grand minima occur of two different types: shorter than 100 years (Maunder-type) and long ≈150 years (Spörer-type). It is also discussed that solar cycles (most possibly not sunspots cycle) could exist during the Grand minima, perhaps with stretched length and asymmetric sunspot latitudinal distribution.These results set new observational constraints on long-term solar and stellar dynamo models.
Historical records of solar grand minima: a review
Authors: Vaquero José M. 
Published: July 2012

AbstractKnowing solar activity during the past centuries is of great interest for many purposes. Historical documents can help us to know about the behaviour of the Sun during the last centuries. The observation of aurorae and naked-eye sunspots provides us with continuous information through the last few centuries that can be used to improve our knowledge of the long-term solar activity including solar Grand Minima. We have more or less detailed information on only one Grand minimum (the Maunder minimum in the second half of 17th century), which serves as an archetype for Grand minima in general. Telescopic sunspot records and measurements of solar diameter during Maunder minimum are available. In this contribution, I review some recent progress on these issues.
Potential energy stored by planets and grand minima events
Authors: Cionco Rodolfo G. 
Published: July 2012

AbstractRecently, Wolff & Patrone (2010), have developed a simple but very interesting model by which the movement of the Sun around the barycentre of the Solar system could create potential energy that could be released by flows pre-existing inside the Sun. The authors claim that it is the first mechanism showing how planetary movements can modify internal structure in the Sun that can be related to solar cycle. In this work we point out limitations of mentioned mechanism (which is based on interchange arguments), which could be inapplicable to a real star. Then, we calculate the temporal evolution of potential energy stored in zones of Sun's interior in which the potential energy could be most efficiently stored taking into account detailed barycentric Sun dynamics. We show strong variations of potential energy related to Maunder Minimum, Dalton Minimum and the maximum of Cycle 22, around 1990. We discuss briefly possible implications of this putative mechanism to solar cycle specially Grand Minima events.
Climate interaction mechanism between solar activity and terrestrial biota
Authors: Osorio-Rosales J. , Mendoza B. 
Published: July 2012

AbstractThe solar activity has been proposed as one of the main factors of Earth's climate variability, however biological processes have been also proposed. Dimethylsulfide (DMS) is the main biogenic sulfur compound in the atmosphere. DMS is mainly produced by the marine biosphere and plays an important role in the atmospheric sulfur cycle. Currently it is accepted that terrestrial biota not only adapts to environmental conditions but influences them through regulations of the chemical composition of the atmosphere. In the present study we used different methods of analysis to investigate the relationship between the DMS, Low Clouds, Ultraviolet Radiation A (UVA) and Sea Surface Temperature (SST) in the Southern Hemisphere. We found that the series analyzed have different periodicities which can be associated with climatic and solar phenomena such as El Niño, the Quasi-Biennial Oscillation (QBO) and the changes in solar activity. Also, we found an anticorrelation between DMS and UVA, the relation between DMS and clouds is mainly non-linear and there is a correlation between DMS and SST. Then, our results suggest a positive feedback interaction among DMS, solar radiation and cloud at time-scales shorter than the solar cycle.
Seeing measurement on Sasahuine mountain, Moquegua, Perú
Authors: Ferradas-Alva C. , Ferrero G. , Huamán M. , Guevara-Day W. , Meza E. , Samanes J. , Becerra P. 
Published: July 2012

AbstractOne of the greatest factors that significantly affect the quality of astronomical images is the atmospheric turbulence causing what we call “seeing”. We present results of the reduction and photometry of astronomical images obtained at the Sasahuine mountain astronomical site (4511 m.a.s.l.), located in the Southern Peruvian Andes, in the department of Moquegua, near the town of Cambrune. These data show preliminary seeing measurements for this site. The present work is part of a bigger investigation program called JANAX which seeks to evaluate potential astronomical observation sites in Peruvian territory through a series of observation missions. The program's aim is to gather data to validate the site for the future construction of a National Astronomical Observatory. The observations were made using an SBIG ST-7MX CCD camera and a BVR standard filter set, attached to a MEADE LX200 356mm telescope.
Creating a sunspot database at the Solar Observatory of Ica National University in Perú
Authors: Martínez-Meneses Lurdes 
Published: July 2012

AbstractWe describe the database and the method used to analyze the sunspot data recorded at the Solar Observatory of the University of Ica in Peru. The parameters that are measured include the relative sunspot number (R), the sunspot area, their positions on the disk, and an estimate of the constant (k) included in R. Sunspots in the database are classified following the Zurich Classification System. From these observations, the active region area, the sunspot rotation speed, and other active regions properties can be estimated.
A solar station in Ica - Mutsumi Ishitsuka: a research center to improve education at the university and schools
Authors: Terrazas-Ramos Raúl 
Published: July 2012

AbstractThe San Luis Gonzaga National University of Ica has built a solar station, in collaboration with the Geophysical Institute of Peru, the National Astronomical Observatory of Japan and the Hida Observatory. The Solar Station has the following equipment: a digital Spectrograph Solar Refractor Telescope Takahashi 15 cm aperture, 60 cm reflector telescope aperture, a magnetometer-MAGDAS/CPNM and a Burst Monitor Telescope Solar-FMT (Project CHAIN). These teams support the development of astronomical science and Ica in Peru, likewise contributing to science worldwide. The development of basic science will be guaranteed when university students, professors and researchers work together. The Solar Station will be useful for studying the different levels of university education and also for the general public. The Solar Station will be a good way to spread science in the region through public disclosure.
Simulation analysis and performance of a feasible GNSS system with multi-beam antennas deployment operating in Galileo frequency bands
Authors: Angelis Constantinos T. 
Published: July 2012

New Global Navigation Satellite System (GNSS) systems under development, such as Galileo, are very promising for future global positioning-based applications. A vast research is undergoing a final stage of implementation in order to fulfill the primary purpose of European Space Agency for developing and then sustaining of 30 (27 + 3 spares) Galileo satellites in orbit. This article presents simulation results for a realistic deployment of multibeam antennas, with a new modified theoretical pattern, in GNSS Satellite Systems. The proposed multibeam antennas use 61-spot beams for maximum efficiency in terms of satellite coverage and accessing high quality of service. In order to prove the reliability and feasibility of this work, various simulations were conducted using the upcoming Galileo system as a platform taking into consideration real-world conditions. Gain analysis versus elevation, Bit Error Rate (BER) and access time simulation results show that the viability of the proposed multibeam antenna deployment is established.
Acyl-homoserine lactone-dependent eavesdropping promotes competition in a laboratory co-culture model
Authors: Chandler Josephine R , Heilmann Silja , Mittler John E , Greenberg E Peter 
Published: July 2012

Abstract
Many Proteobacteria use acyl-homoserine lactone (AHL)-mediated quorum sensing to activate the production of antibiotics at high cell density. Extracellular factors like antibiotics can be considered public goods shared by individuals within a group. Quorum-sensing control of antibiotic production may be important for protecting a niche or competing for limited resources in mixed bacterial communities. To begin to investigate the role of quorum sensing in interspecies competition, we developed a dual-species co-culture model using the soil saprophytes Burkholderia thailandensis (Bt) and Chromobacterium violaceum (Cv). These bacteria require quorum sensing to activate the production of antimicrobial factors that inhibit growth of the other species. We demonstrate that quorum-sensing-dependent antimicrobials can provide a competitive advantage to either Bt or Cv by inhibiting growth of the other species in co-culture. Although the quorum-sensing signals differ for each species, we show that the promiscuous signal receptor encoded by Cv can sense signals produced by Bt, and that this ability to eavesdrop on Bt can provide Cv an advantage in certain situations. We use an in silico approach to investigate the effect of eavesdropping in competition, and show conditions where early activation of antibiotic production resulting from eavesdropping can promote competitiveness. Our work supports the idea that quorum sensing is important for interspecies competition and that promiscuous signal receptors allow eavesdropping on competitors in mixed microbial habitats.
Overcoming multidrug-resistance in vitro and in vivo using the novel P-glycoprotein inhibitor 1416
Authors: Xu Yan , Zhi Feng , Xu Guangming , Tang Xiaolei , Lu Sheng , Wu Jinhui , Hu Yiqiao 
Published: July 2012

MDR (multidrug-resistance) represents a major obstacle to successful cancer chemotherapy and is usually accomplished by overexpression of P-gp (P-glycoprotein). Much effort has been devoted to developing P-gp inhibitors to modulate MDR. However, none of the inhibitors on the market have been successful. 1416 [1-(2,6-dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino)propane hydrochloride (phenoprolamine hydrochloride)] is a new VER (verapamil) analogue with a higher IC50 for blocking calcium channel currents than VER. In the present paper, we examined the inhibition effect of 1416 on P-gp both in vitro and in vivo. 1416 significantly enhanced cytotoxicity of VBL (vinblastine) in P-gp-overexpressed human multidrug-resistant K562/ADM (adriamycin) and KBV cells, but had no such effect on the parent K562 and KB cells. The MDR-modulating function of 1416 was further confirmed by increasing intracellular Rh123 (rhodanmine123) content in MDR cells. Human K562/ADM xenograft-nude mice model verified that 1416 potentiates the antitumour activity of VBL in vivo. RT-PCR (reverse transcriptase-PCR) and FACS analysis demonstrated that the expression of MDR1/P-gp was not affected by 1416 treatment. All these observations suggest that 1416 could be a promising agent for overcoming MDR in cancer chemotherapy.
Population Genetics of Southern Flounder with Implications for Management
Authors: Anderson J. D. , Karel W. J. 
Published: July 2012

Abstract
The southern flounder Paralichthys lethostigma is a marine flatfish that ranges from North Carolina to the Yucatan Peninsula in the Gulf of Mexico. Management of southern flounder will be improved by proper delineation of management units based on genetic data. We used microsatellite DNA markers to determine how many populations exist across the species’ range and the geographic extent of those populations. Based on significant genetic divergence across loci (F CT = 0.035), two discrete populations of southern flounder occur. The populations inhabit the Gulf of Mexico and Atlantic Ocean, with the boundary between them located in southern Florida, an area that is generally devoid of southern flounder. Within the Gulf of Mexico, there was little evidence of discrete populations but weak evidence for isolation by distance. These data indicate that specieswide management of southern flounder should account for the independent demographic entities in the Gulf and Atlantic and that local management strategies should account for the upper limits to dispersal within the Gulf.
Received January 12, 2012; accepted April 12, 2012
Structure and piezoelectric properties of (1 − 0.5x)BaTiO3–0.5x (0.4BaZrO3–0.6CaTiO3) ceramics
Authors: Liu Laijun , Zheng Shaoying , Huang Yanming , Shi Danping , Wu Shuangshuang , Fang Liang , Hu Changzheng , Elouadi Brahim 
Published: July 2012

Abstract
(1 − 0.5x)BaTiO3–0.5x (0.4BaZrO3–0.6CaTiO3) (0 ⩽ x ⩽ 0.875) ceramics were fabricated by a conventional solid-state technique. The influence of the substitution content on crystallographic structure, phase transition, piezoelectric and ferroelectric properties was investigated. A morphotropic phase boundary from a cubic–rhombohedral–tetragonal tricritical triple point was found in x = 0.375–0.500. The sample with x = 0.375, sintered at a lower temperature (1623 K), showed excellent piezoelectric performance (d
33 = 420 pC N−1, k
p = 57%, Q
m = 120.2 and T
C = 380 K) and good thermal stability up to 370 K.
Integrated real-time control of MHD instabilities using multi-beam ECRH/ECCD systems on TCV
Authors: Felici F. , Goodman T.P. , Sauter O. , Canal G. , Coda S. , Duval B.P. , Rossel J.X. 
Published: July 2012

Abstract
Simultaneous real-time control of multiple MHD instabilities is experimentally demonstrated in the TCV tokamak. Multiple sources of EC heating and current drive, injected through real-time controlled launchers, are used to stabilize 3/2 and 2/1 neoclassical tearing modes (NTMs) rapidly after their appearance. Control of the sawtooth instability using a new sawtooth-pacing technique is demonstrated, providing precise control of the time of appearance of the sawtooth crash. Efficient NTM preemption can then be performed by applying pulsed power on the mode rational surface at the time of the seed-island generating sawtooth crash. These three elements are combined into one integrated control system which can simultaneously control the sawtooth period, preempt the formation of NTMs and suppress these if they appear.
A potentially robust plasma profile control approach for ITER using real-time estimation of linearized profile response models
Authors: Kim S.H. , Lister J.B. 
Published: July 2012

Abstract
An active plasma profile control approach for ITER, which is potentially robust by being tolerant to changing and uncertain physics, has been explored in this work, using a technique based on real-time estimation of linearized profile response models. The linearized models approximate static responses of the plasma profiles to power changes in auxiliary heating and current drive systems. These models are updated in real-time, differing from the model-based technique which deduces a dynamic model from identification experiments. The underlying physics is simplified with several assumptions to allow real-time update of the profile response models; however, without significant loss of information necessary for feedback control of the plasma profiles. The response of the electron temperature profile is modelled by simplifying the electron heat transport equation. The response of the safety factor profile is computed by directly relating it to the changes in source current density profiles. The required actuator power changes are directly computed by inverting the response matrix using the singular value decomposition technique. The saturation of the actuator powers is taken into account and the capability of using quantized auxiliary powers is provided. The potential of our active control approach has been tested by applying it to simulations of the ITER hybrid mode operation using CRONOS. In these simulations, either a global transport model or a theory-based local transport model has been used and the electron temperature and safety factor profiles were well controlled either independently or simultaneously.
Sawtooth period control strategies and designs for improved performance
Authors: Witvoet G. , Steinbuch M. , de Baar M.R. , Doelman N.J. , Westerhof E. 
Published: July 2012

Abstract
The sawtooth instability is associated with the triggering of neo-classical tearing modes, core fuelling, α-confinement and the exhaust of thermal helium. Sawtooth control is therefore important for optimal reactor performance in ELMy H-modes. Control schemes for the sawtooth period have been published in the literature, but the systematic design of high-performance controllers (yielding accurate and fast convergent responses) has not been addressed. In this work, three control strategies for high-performance sawtooth control are presented using electron cyclotron current drive (ECCD). Both degrees of freedom of the ECCD actuator will be explored and combined with advanced controller designs. First, the ECCD deposition location is used as a control variable, for which a gain-scheduled feedback controller and static feedforward control is derived. Second, the use of the driven current as a control variable is explored, and a simple controller is designed based on the identified dynamics. In the third approach both control variables are joined in an overall controller design, which enables the combination of high-performance control of the sawtooth period and control of the gyrotron power. Time-domain simulations with a combined Kadomtsev–Porcelli sawtooth model show that each strategy obtains a better closed-loop performance than standard linear feedback techniques on merely the deposition location.
Thermoelectric currents and their role during ELM formation in JET
Authors: Rack M. , Wingen A. , Liang Y. , Spatschek K.H. , Harting D.M. , Devaux S. 
Published: July 2012

Abstract
A recently developed numerical model, describing a self-amplification and structure formation process which is used to model the initial non-linear growth phase of edge-localized modes (ELMs), is applied to the JET tokamak. Connection length simulations of the magnetic topology, including only error fields, for JET reveal the existence of small, so-called short connection length flux tubes. Such a configuration is used as the starting point for the model. Thermoelectric currents are assumed to flow in the short connection length flux tubes and add additional magnetic perturbations which change the magnetic topology severely. The change in magnetic topology leads to the formation of new, much larger short connection length flux tubes that can conduct much larger currents through the plasma edge. The current density inside the flux tubes is assumed to be constant to calculate the total current. This self-amplification process leads to the formation of patterns, known as footprints, on various segments of the inner wall throughout the vessel. The resulting footprints and their relation to the observed ELM patterns during discharges are discussed.
Pellet fuelling requirements to allow self-burning on a helical-type fusion reactor
Authors: Sakamoto R. , Miyazawa J. , Yamada H. , Masuzaki S. , Sagara A. 
Published: July 2012

Abstract
Pellet refuelling conditions to sustain a self-burning plasma have been investigated by extrapolating the confinement property of the LHD plasma, which appears to be governed by a gyro-Bohm-type confinement property. The power balance of the burning plasma is calculated taking into account the profile change with pellet deposition and subsequent density relaxation. A self-burning plasma is achieved within the scope of conventional pellet injection technology. However, a very small burn-up rate of 0.18% is predicted. Higher velocity pellet injection is effective in improving the burn-up rate by deepening particle deposition, whereas deep fuelling leads to undesirable fluctuation of the fusion output.
Biomass size spectra of mesozooplankton in the Chukchi Sea during the summers of 1991/1992 and 2007/2008: an analysis using optical plankton counter data
Authors: Matsuno Kohei , Yamaguchi Atsushi , Imai Ichiro 
Published: July 2012

AbstractMatsuno, K., Yamaguchi, A., and Imai, I. 2012. Biomass size spectra of mesozooplankton in the Chukchi Sea during the summers of 1991/1992 and 2007/2008: an analysis using optical plankton counter data. – ICES Journal of Marine Science, 69: . An optical plankton counter was used to examine the regional characteristics of the zooplankton communities in the Chukchi Sea during the summers of 1991, 1992, 2007, and 2008. Zooplankton abundance and biomass ranged from 5000 to 1 170 000 ind. m−2 and 0.2 to 10.9 g dry mass m−2, respectively. Based on zooplankton biovolume in equivalent spherical diameter (ESD) in 48 bins, one every 0.1 mm between 0.25 and 5.0 mm, a Bray–Curtis cluster analysis classified zooplankton communities into four groups (A–D). No changes were observed in zooplankton communities south of the Lisburne Peninsula (group A) throughout the 4 years, but there were differences north of the Peninsula, with group B (normal, intermediate biomass) observed in 1991/1992, group D (low biomass) in 2007, and group C (predominance of barnacle larvae) in 2008. Analysis of the normalized biomass size spectra for the groups indicated that groups A and C were very productive, so the zooplankton community south of the Lisburne Peninsula was consistently highly productive, which may be because of the continuous inflow of Pacific Water rich in nutrients. Zooplankton communities north of the Lisburne Peninsula varied greatly from year to year, which may be related to interannual changes in sea-ice extent.