bluuebunny/crossref_metadata_2025 huggingface dataset:
Competition between intercellular adhesion molecule‐1 and a small‐molecule antagonist for a common binding site on the αl subunit of lymphocyte function‐associated antigen‐1
Authors: Keating Susan M. , Clark Kevin R. , Stefanich Lisa D. , Arellano Fred , Edwards Caroline P. , Bodary Sarah C. , Spencer Steven A. , Gadek Thomas R. , Marsters James C. , Beresini Maureen H.
Published: December 2005

The lymphocyte function‐associated antigen‐1 (LFA‐1) binding of a unique class of small‐molecule antagonists as represented by compound 3 was analyzed in comparison to that of soluble intercellular adhesion molecule‐1 (sICAM‐1) and A‐286982, which respectively define direct and allosteric competitive binding sites within LFA‐1's inserted (I) domain. All three molecules antagonized LFA‐1 binding to ICAM‐1‐Immunoglobulin G fusion (ICAM‐1‐Ig) in a competition ELISA, but only compound 3 and sICAM‐1 inhibited the binding of a fluorescein‐labeled analog of compound 3 to LFA‐1. Compound 3 and sICAM‐1 displayed classical direct competitive binding behavior with ICAM‐1. Their antagonism of LFA‐1 was surmountable by both ICAM‐1‐Ig and a fluorescein‐labeled compound 3 analog. The competition of both sICAM‐1 and compound 3 with ICAM‐1‐Ig for LFA‐1 resulted in equivalent and linear Schild plots with slopes of 1.24 and 1.26, respectively. Cross‐linking studies with a photoactivated analog of compound 3 localized the high‐affinity small‐molecule binding site to the N‐terminal 507 amino acid segment of the α chain of LFA‐1, a region that includes the I domain. In addition, cells transfected with a variant of LFA‐1 lacking this I domain showed no significant binding of a fluorescein‐labeled analog of compound 3 or ICAM‐1‐Ig. These results demonstrate that compound 3 inhibits the LFA‐1/ICAM‐1 binding interaction in a directly competitive manner by binding to a high‐affinity site on LFA‐1. This binding site overlaps with the ICAM‐1 binding site on the α subunit of LFA‐1, which has previously been localized to the I domain.
The allosteric transition in DnaK probed by infrared difference spectroscopy. Concerted ATP‐induced rearrangement of the substrate binding domain
Authors: Moro Fernando , Fernández‐Sáiz Vanesa , Muga Arturo
Published: December 2005

The biological activity of DnaK, the bacterial representative of the Hsp70 protein family, is regulated by the allosteric interaction between its nucleotide and peptide substrate binding domains. Despite the importance of the nucleotide‐induced cycling of DnaK between substrate‐accepting and releasing states, the heterotropic allosteric mechanism remains as yet undefined. To further characterize this mechanism, the nucleotide‐induced absorbance changes in the vibrational spectrum of wild‐type DnaK was characterized. To assign the conformation sensitive absorption bands, two deletion mutants (one lacking the C‐terminal α‐helical subdomain and another comprising only the N‐terminal ATPase domain), and a single‐point DnaK mutant (T199A) with strongly reduced ATPase activity, were investigated by time‐resolved infrared difference spectroscopy combined with the use of caged‐nucleotides. The results indicate that (1) ATP, but not ADP, binding promotes a conformational change in both subdomains of the peptide binding domain that can be individually resolved; (2) these conformational changes are kinetically coupled, most likely to ensure a decrease in the affinity of DnaK for peptide substrates and a concomitant displacement of the lid away from the peptide binding site that would promote efficient diffusion of the released peptide to the medium; and (3) the α‐helical subdomain contributes to stabilize the interdomain interface against the thermal challenge and allows bidirectional transmission of the allosteric signal between the ATPase and substrate binding domains at stress temperatures (42°C).
High resolution structure of the HDGF PWWP domain: A potential DNA binding domain
Authors: Lukasik Stephen M. , Cierpicki Tomasz , Borloz Matthew , Grembecka Jolanta , Everett Allen , Bushweller John H.
Published: December 2005

Hepatoma Derived Growth Factor (HDGF) is an endogenous nuclear‐targeted mitogen that is linked with human disease. HDGF is a member of the weakly conserved PWWP domain family. This 70–amino acid motif, originally identified from the WHSC1 gene, has been found in more than 60 eukaryotic proteins. In addition to the PWWP domain, many proteins in this class contain known chromatin remodeling domains, suggesting a role for HDGF in chromatin remodeling. We have determined the NMR structure of the HDGF PWWP domain to high resolution using a combination of NOEs, J‐couplings, and dipolar couplings. Comparison of this structure to a previously determined structure of the HDGF PWWP domain shows a significant difference in the C‐terminal region. Comparison to structures of other PWWP domains shows a high degree of similarity to the PWWP domain structures from Dnmt3b and mHRP. The results of selected and amplified binding assay and NMR titrations with DNA suggest that the HDGF PWWP domain may function as a nonspecific DNA‐binding domain. Based on the NMR titrations, we propose a model of the interaction of the PWWP domain with DNA.
Effective cotranslational folding of firefly luciferase without chaperones of the Hsp70 family
Authors: Svetlov Maxim S. , Kommer Aigar , Kolb Vyacheslav A. , Spirin Alexander S.
Published: December 2005

Molecular chaperones of the Hsp70 family (bacterial DnaK, DnaJ, and GrpE) were shown to be strictly required for refolding of firefly luciferase from a denatured state and thus for effective restoration of its activity. At the same time the luciferase was found to be synthesized in an Escherichia coli cell‐free translation system in a highly active state in the extract with no chaperone activity. The addition of the chaperones to the extract during translation did not raise the activity of the enzyme. The abrupt arrest of translation by the addition of a translational inhibitor led to immediate cessation of the enzyme activity accumulation, indicating the cotranslational character of luciferase folding. The results presented suggest that the chaperones of the Hsp70 family are not required for effective cotranslational folding of firefly luciferase.
Finding biologically relevant protein domain interactions: Conserved binding mode analysis
Authors: Shoemaker Benjamin A. , Panchenko Anna R. , Bryant Stephen H.
Published: December 2005

Proteins evolved through the shuffling of functional domains, and therefore, the same domain can be found in different proteins and species. Interactions between such conserved domains often involve specific, well‐determined binding surfaces reflecting their important biological role in a cell. To find biologically relevant interactions we developed a method of systematically comparing and classifying protein domain interactions from the structural data. As a result, a set of conserved binding modes (CBMs) was created using the atomic detail of structure alignment data and the protein domain classification of the Conserved Domain Database. A conserved binding mode is inferred when different members of interacting domain families dock in the same way, such that their structural complexes superimpose well. Such domain interactions with recurring structural themes have greater significance to be biologically relevant, unlike spurious crystal packing interactions. Consequently, this study gives lower and upper bounds on the number of different types of interacting domain pairs in the structure database on the order of 1000–2000. We use CBMs to create domain interaction networks, which highlight functionally significant connections by avoiding many infrequent links between highly connected nodes. The CBMs also constitute a library of docking templates that may be used in molecular modeling to infer the characteristics of an unknown binding surface, just as conserved domains may be used to infer the structure of an unknown protein. The method's ability to sort through and classify large numbers of putative interacting domain pairs is demonstrated on the oligomeric interactions of globins.
Acid destabilization of the solution conformation of Bcl‐XL does not drive its pH‐dependent insertion into membranes
Authors: Thuduppathy Guruvasuthevan R. , Hill R. Blake
Published: December 2005

Regulation of programmed cell death by Bcl‐xL is dependent on both its solution and integral membrane conformations. A conformational change from solution to membrane is also important in this regulation. This conformational change shows a pH‐dependence similar to the translocation domain of diphtheria toxin, where an acid‐induced molten globule conformation in the absence of lipid vesicles mediates the change from solution to membrane conformations. By contrast, Bcl‐xLΔTM in the absence of lipid vesicles exhibits no gross conformational changes upon acidification as observed by near‐ and far‐UV circular dichroism spectropolarimetry. Additionally, no significant local conformational changes upon acidification were observed by heteronuclear NMR spectroscopy of Bcl‐xLΔTM. Under conditions that favor the solution conformation (pH 7.4), the free energy of folding for Bcl‐xLΔTM (ΔG°) was determined to be 15.8 kcal·mol−1. Surprisingly, under conditions that favor a membrane conformation (pH 4.9), ΔG° was 14.6 kcal·mol−1. These results differ from those obtained with many other membrane‐insertable proteins where acid‐induced destabilization is important. Therefore, other contributions must be necessary to destabilize the solution conformation Bcl‐xL and favor the membrane conformation at pH 4.9. Such contributions might include the presence of a negatively charged membrane or an electrostatic potential across the membrane. Thus, for proteins that adopt both solution and membrane conformations, an obligatory molten globule intermediate may not be necessary. The absence of a molten globule intermediate might have evolved to protect Bcl‐xL from intracellular proteases as it undergoes this conformational change essential for its activity.
Effects of solutes on solubilization and refolding of proteins from inclusion bodies with high hydrostatic pressure
Authors: Lee Seung‐Hyun , Carpenter John F. , Chang Byeong S. , Randolph Theodore W. , Kim Yong‐Sung
Published: December 2005

High hydrostatic pressure (HHP)‐mediated solubilization and refolding of five inclusion bodies (IBs) produced from bacteria, three Gram‐negative binding proteins (GNBP1, GNBP2, and GNBP3) from Drosophila, and two phosphatases from human were investigated in combination of a redox‐shuffling agent (2 mM DTT and 6 mM GSSG) and various additives. HHP (200 MPa) combined with the redox‐shuffling agent resulted in solubilization yields of ∼42%–58% from 1 mg/mL of IBs. Addition of urea (1 and 2 M), 2.5 M glycerol, L‐arginine (0.5 M), Tween 20 (0.1 mM), or Triton X‐100 (0.5 mM) significantly enhanced the solubilization yield for all proteins. However, urea, glycerol, and nonionic surfactants populated more soluble oligomeric species than monomeric species, whereas arginine dominantly induced functional monomeric species (∼70%–100%) to achieve refolding yields of ∼55%–78% from IBs (1 mg/mL). Our results suggest that the combination of HHP with arginine is most effective in enhancing the refolding yield by preventing aggregation of partially folded intermediates populated during the refolding. Using the refolded proteins, the binding specificity of GNBP2 and GNBP3 was newly identified the same as with that of GNBP1, and the enzymatic activities of the two phosphatases facilitates their further characterization.
pH driven conformational dynamics and dimer‐to‐monomer transition in DLC8
Authors: Mohan P.M. Krishna , Barve Maneesha , Chatterjee Amarnath , Hosur Ramakrishna V.
Published: December 2005

Dynein light chain protein, a part of the cytoplasmic motor assembly, is a homodimer at physiological pH and dissociates below pH 4.5 to a monomer. The dimer binds to a variety of cargo, whereas the monomer does not bind any of the target proteins. We report here the pH induced stepwise structural and motional changes in the protein, as derived from line broadening and 15N transverse relaxation measurements. At pH 7 and below until 5, partial protonation and consequent interconversion between molecules carrying protonated and neutral histidines, causes conformational dynamics in the dimeric protein and this increases with decreasing pH. Enhanced dynamics in turn leads to partial loosening of the structure. This would have implications for different efficacies of binding by target proteins due to small variations in pH in different parts of the cell, and hence for cargo trafficking from one part to another. Below pH 5, enhanced charge repulsions, partial loss of hydrophobic interactions, and destabilization of H‐bonds across the dimer interface cause further loosening of the dimeric structure, leading eventually to the dissociation of the dimer.
Plasmodium falciparum glutathione S‐transferase—Structural and mechanistic studies on ligand binding and enzyme inhibition
Authors: Hiller Nicole , Fritz‐Wolf Karin , Deponte Marcel , Wende Wolfgang , Zimmermann Herbert , Becker Katja
Published: December 2005

Glutathione S‐transferase of the malarial parasite Plasmodium falciparum (PfGST) represents a novel class of GST isoenzymes. Since the architecture of the PfGST substrate binding site differs significantly from its human counterparts and there is only this one isoenzyme present in the parasite, PfGST is considered a highly attractive target for antimalarial drug development. Here we report the mechanistic, kinetic, and structural characterization of PfGST as well as its interaction with different ligands. Our data indicate that in solution PfGST is present as a tetramer that dissociates into dimers in the presence of glutathione (GSH). Fluorescence spectroscopy shows that in the presence of GSH GST serves as ligandin for parasitotoxic ferriprotoporphyrin IX with a high‐ and a low‐affinity binding site. This is supported by a clear uncompetitive inhibition type. Site‐directed mutagenesis studies demonstrate that neither Cys 86 nor Cys 101 contribute to the peroxidase activity of the enzyme, which is thus performed GSH‐dependently at the active site. Tyr 9 is responsible for the deprotonation of GSH and Lys 15, but also Gln 71 are involved in GSH binding. We furthermore report the 2.4 Å resolution X‐ray structure of PfGST cocrystallized with the inhibitor S‐hexylglutathione. In comparison with a previously reported structure obtained by crystal soaking, differences occur at the C‐terminal end of helix α4 and at the S‐hexylmoiety of the inhibitor. We furthermore show that, in contrast to previous reports, the antimalarial drug artemisinin is not metabolized by PfGST.
Solution structure of the N‐terminal A domain of the human voltage‐gated Ca2+channel β4a subunit
Authors: Vendel Andrew C. , Rithner Christopher D. , Lyons Barbara A. , Horne William A.
Published: December 2005

Ca2+ channel β subunits regulate trafficking and gating (opening and closing) of voltage‐dependent Ca2+ channel α 1 subunits. Based on primary sequence comparisons, they are thought to be modular structures composed of five domains (A–E) that are related to the large family of membrane associated guanylate‐kinase (MAGUK) proteins. The crystal structures of the β subunit core, B–D, domains have recently been reported; however, very little is known about the structures of the A and E domains. The N‐terminal A domain is a hypervariable region that differs among the four subtypes of Ca2+ channel β subunits (β1–β4). Furthermore, this domain undergoes alternative splicing to create multiple N‐terminal structures within a given gene class that have distinct effects on gating. We have solved the solution structure of the A domain of the human β4a subunit, a splice variant that we have shown previously to have α 1 subunit subtype‐specific effects on Ca2+ channel trafficking and gating.
Crystal structure of the probable haloacid dehalogenase PH0459 from Pyrococcus horikoshii OT3
Authors: Arai Ryoichi , Kukimoto‐Niino Mutsuko , Kuroishi Chizu , Bessho Yoshitaka , Shirouzu Mikako , Yokoyama Shigeyuki
Published: December 2005

PH0459, from the hyperthermophilic archaeon Pyrococcus horikoshii OT3, is a probable haloacid dehalogenase with a molecular mass of 26,725 Da. Here, we report the 2.0 Å crystal structure of PH0459 (PDB ID: 1X42) determined by the multiwavelength anomalous dispersion method. The core domain has an α/β structure formed by a six‐stranded parallel β‐sheet flanked by six α‐helices and three 310‐helices. One disulfide bond, Cys186–Cys212, forms a bridge between an α‐helix and a 310‐helix, although PH0459 seems to be an intracellular protein. The subdomain inserted into the core domain has a four‐helix bundle structure. The crystal packing suggests that PH0459 exists as a monomer. A structural homology search revealed that PH0459 resembles the l‐2‐haloacid dehalogenases l‐DEX YL from Pseudomonas sp. YL and DhlB from Xanthobacter autotrophicus GJ10. A comparison of the active sites suggested that PH0459 probably has haloacid dehalogenase activity, but its substrate specificity may be different. In addition, the disulfide bond in PH0459 probably facilitates the structural stabilization of the neighboring region in the monomeric form, although the corresponding regions in l‐DEX YL and DhlB may be stabilized by dimerization. Since heat‐stable dehalogenases can be used for the detoxification of halogenated aliphatic compounds, PH0459 will be a useful target for biotechnological research.
Solution structure of the C4 zinc finger domain of HDM2
Authors: Yu Grace W. , Allen Mark D. , Andreeva Antonina , Fersht Alan R. , Bycroft Mark
Published: December 2005

HDM2 is a ubiquitin E3 ligase that is a key negative regulator of the tumor suppressor p53. Here, we report the determination of the solution structure of the C4 zinc finger domain of HDM2 using multidimensional NMR. The HDM2 C4 zinc finger domain has a fold consisting of a 310 helix followed by four β‐strands, which shares significant structural similarity to the zinc ribbon protein family. Family based sequence analysis identified two putative binding sites, one of which resembles an RNA binding motif.
GALILEO'S HERITAGE: PLANETS, ARTS AND HISTORY
Authors: BIGNAMI GIOVANNI F.
Published: December 2005

Everyone knows Galileo Galilei as an astronomer, physicist and writer of books that changed our perception of the world. Few people know that Galileo also wrote poetry in elegant XVI century Italian. In 1590, aged 26, Galileo was a lecturer of mathematics at the University of Pisa, the poorest paid of the faculty. He dutifully taught Euclid, but quickly ran into trouble: he despised and openly challenged Pisa's strict academic traditions. Especially the rule by which all professors had to wear their gown at all times, under penalty of a stiff fine. To chastise and mock such rule, he wrote his longest poem, the 301-line Capitolo "Against the Donning of the Gown".
BRUNO ROSSI AND THE GROUP OF ARCETRI
Authors: SCARSI LIVIO
Published: December 2005

A tribute to Bruno Rossi. A sketch is given of the sparkling period of the research on Cosmic Rays in Florence by Rossi and his Team. The Group of Arcetri flared up as a meteor on the "Tuscan Hill" which has seen Galileo as a solitary giant opening a new era in Physics some centuries before.
ULTRA HIGH ENERGY COSMIC RAYS
Authors: BLASI PASQUALE
Published: December 2005

The origin of the cosmic rays at energies in excess of 1020 eV is puzzling the scientific community for several decades now. The mystery adds to the general problem of understanding the nature of the bulk of cosmic rays, that are usually assumed to be accelerated within the Milky Way. Here we summarize the main elements of the observations and propose some possible avenues to interpret these data. The upcoming experiments for the detection of ultra high energy cosmic rays are expected to find the answers to many of our current open problems, and in particular to lead to the identification of the sources.
A UNIFIED MODEL OF HIGH-ENERGY ASTROPHYSICAL PHENOMENA
Authors: DE RÚJULA A.
Published: December 2005

I outline a unified model of high-energy astrophysics, in which the gamma background radiation, cluster "cooling flows", gamma-ray bursts, X-ray flashes and cosmic-ray electrons and nuclei of all energies — share a common origin. The mechanism underlying these phenomena is the emission of relativistic "cannonballs" by ordinary supernovae, analogous to the observed ejection of plasmoids by quasars and microquasars. I concentrate on Cosmic Rays: the longest-lasting conundrum in astrophysics. The distribution of Cosmic Rays in the Galaxy, their total "luminosity", the broken power-law spectra with their observed slopes, the position of the knee(s) and ankle(s), and the alleged variations of composition with energy are all explained in terms of simple and "standard" physics. The model is only lacking a satisfactory theoretical understanding of the "cannon" that emits the cannonballs in catastrophic episodes of accretion onto a compact object.
MODELS AND PHENOMENOLOGY
Authors: ERLYKIN A. D.
Published: December 2005

It is evident that models of the knee should match the observational phenomenology. In this talk I discuss a few aspects of phenomenology, which are important not only for the understanding of the knee origin, but also for the general problem of the origin of cosmic rays. Among them are the shape of the energy spectrum, its irregularity, the sharpness of the knee and its fine structure. The classification of models is given and some examples of the most recent models are discussed. The most probable conclusion deduced from this examination is that the knee has an astrophysical origin and the so called 'source' models of the knee are most likely among them.
PHYSICS OF SUPERNOVAE
Authors: NADYOZHIN D. K. , IMSHENNIK V. S.
Published: December 2005

The origin of cosmic rays (CR) is supposed to be closely connected with supernovae (SNe) which create the conditions favorable for various mechanisms of the CR acceleration to operate effectively. First, modern ideas about the physics of the SN explosion are briefly discussed: the explosive thermonuclear burning in degenerate white dwarfs resulting in Type Ia SNe and the gravitational collapse of stellar cores giving rise to other types of SNe (Ib, Ic, IIL, IIP). Next, we survey some global properties of the SNe of different types: the total explosion energy distribution of various components (kinetic energy of the hydrodynamic flow, electromagnetic radiation, temporal behavior of the neutrino emission and individual energies of different neutrino flavors). Then, we discuss in the possibility of direct hydrodynamic acceleration by the shock wave breakout and the properties of the SN shocks in the circumstellar medium. Then the properties of the neutrino radiation from the core-collapse SNe and a possibility to incorporate both the LSD Mont Blanc neutrino event and that recorded by the K II and IMB detectors into a single scenario are described in detail. Finally, the issues of the neutrino nucleosynthesis and of the connection between supernova and gamma-ray bursts are discussed.
COSMIC RAYS AND COSMOLOGY
Authors: WIBIG TADEUSZ , WOLFENDALE ARNOLD W.
Published: December 2005

Two aspects of cosmic rays and cosmology are considered here. Firstly, the relevance of extragalactic cosmic rays to the radiation – and magnetic – fields in the Universe and secondly the contribution of Galactic cosmic rays (or other entities allied to them) to the 'foreground' in analysis of the cosmic microwave background (CMB). Concerning the latter, we present evidence strongly suggesting that the foreground is, indeed, important. Coupled with the demonstration of asymmetries, of Galactic form, in the CMB maps the case for changes to the presently-derived cosmological parameters is strong.
ENERGETIC PARTICLES IN THE HELIOSPHERE
Authors: HEBER BERND
Published: December 2005

The heliosphere is the region around the Sun that is filled by the solar wind and its embedded magnetic field. The interaction of the supersonic solar wind with the local interstellar medium leads to a transition from supersonic to subsonic speeds at the heliospheric termination shock. The latter is regarded to be the source of the anomalous component of cosmic rays. Within the heliosphere "local" energetic particle sources, like the Sun and interplanetary shock waves contribute to the cosmic ray flux, too. At energies below a few GeV the observed galactic and anomalous cosmic ray intensities are modulated by the heliospheric magnetic field. In my contribution, both the current knowledge and hypotheses about modulation and the transport of cosmic rays in the heliosphere are reviewed.
ISOTOPIC COMPOSITION OF COSMIC RAYS: RESULTS FROM THE COSMIC RAY ISOTOPE SPECTROMETER ON THE ACE SPACECRAFT
Authors: ISRAEL M. H.
Published: December 2005

Over the past seven years the Cosmic Ray Isotope Spectrometer (CRIS) on the ACE spacecraft has returned data with an unprecedented combination of excellent mass resolution and high statistics, describing the isotopic composition of elements from lithium through nickel in the energy interval ~ 50 to 500 MeV/nucleon. These data have demonstrated:

* The time between nucleosynthesis and acceleration of the cosmic-ray nuclei is at least 105 years. The supernova in which nucleosynthesis takes place is thus not the same supernova that accelerates a heavy nucleus to cosmic-ray energy.

* The mean confinement time of cosmic rays in the Galaxy is 15 Myr.

* The isotopic composition of the cosmic-ray source is remarkably similar to that of solar system. The deviations that are observed, particularly at 22 Ne and 58 Fe , are consistent with a model in which the cosmic-ray source is OB associations in which the interstellar medium has solar-system composition enriched by roughly 20% admixture of ejecta from Wolf-Rayet stars and supernovae.

* Cosmic-ray secondaries that decay only by electron capture provide direct evidence for energy loss of cosmic rays as they penetrate the solar system.

This invited overview paper at ECRS 19 was largely the same as an invited paper presented a month earlier at the 8th Nuclei in the Cosmos Conference in Vancouver. The proceedings of that conference will be published shortly by Elsevier as a special edition of Nuclear Physics A. For further summary of results from CRIS, the reader is referred to URL 〈〉 and links on that page to CRIS and to Science News.
SOLAR ENERGETIC PARTICLES
Authors: KIRÁLY PÉTER
Published: December 2005

Energetic particles recorded in the Earth environment and in interplanetary space have a multitude of origins, i.e. acceleration and propagation histories. At early days practically all sufficiently energetic particles were considered to have come either from solar flares or from interstellar space. Later on, co-rotating interplanetary shocks, the termination shock of the supersonic solar wind, planetary bow shocks and magnetospheres, and also coronal mass ejections (CME) were recognized as energetic particle sources. It was also recognized that less energetic (suprathermal) particles of solar origin and pick-up ions have also a vital role in giving rise to energetic particles in interplanetary disturbances. The meaning of the term "solar energetic particles" (SEP) is now somewhat vague, but essentially it refers to particles produced in disturbances fairly directly related to solar processes. Variation of intensity fluctuations with energy and with the phase of the solar cycle will be discussed. Particular attention will be given to extremes of time variation, i.e. to very quiet periods and to large events. While quiet-time fluxes are expected to shed light on some basic coronal processes, large events dominate the fluctuation characteristics of cumulated fluence, and the change of that fluctuation with energy and with the phase of the solar cycle may also provide important clues. Mainly ISEE-3 and long-term IMP-8 data will be invoked. Energetic and suprathermal particles that may never escape into interplanetary space may play an important part in heating the corona of the sun.
CORRELATED MEASUREMENTS OF THE SECONDARY COSMIC RAY FLUXES BY THE NEUTRON MONITORS AND MUON TELESCOPES
Authors: CHILINGARIAN A. , BABAYAN V. , BOSTANJYAN N. , KARAPETYAN G.
Published: December 2005

Radiation and Geomagnetic storms, which are elements of Space Weather, are part of the major obstacles for Space Operations. Reliable forecasting of the arrival of these dangerous elements is of vital importance for the orbiting flights and electric power distribution in near polar regions. In addition to the fleet of space-born instruments, worldwide networks of particle detectors spread along different latitudes and longitudes, provide valuable information on the intensity and anisotropy of the variable cosmic ray fluxes.

Aragats Space-Environmental Center provides monitoring of the different species of secondary cosmic rays at two altitudes and with different energy thresholds. 1-minute data is available on-line from URL 〈〉. We demonstrated the sensitivity of the different species of secondary cosmic ray flux to geophysical conditions, taking as examples extremely violent events of end of October – November 2003. Also we introduce the correlation analysis of the different components of registered time-series as a new tool for the classification of the geoeffective events.
SOLAR NEUTRON EVENTS THAT HAVE BEEN FOUND IN SOLAR CYCLE 23
Authors: FLÜCKIGER E. O. , BÜTIKOFER R. , CHILINGARIAN A. , HOVSEPYAN G. , TAN Y. H. , YUDA T. , TSUCHIYA H. , OHNISHI M. , KATAYOSE Y. , MURAKI Y. , MATSUBARA Y. , SAKO T. , WATANABE K. , MASUDA S. , SAKAI T. , SHIBATA S. , OGASAWARA R. , MIZUMOTO Y. , NAKAGIRI M. , MIYASHITA A. , STOKER P. H. , LOPATE C. , KUDELA K. , GROS M.
Published: December 2005

In this paper, we report solar neutron events detected in the solar cycle 23, especially three interesting events detected on November 23rd and 28th 1998 in Tibet and October 28th 2003 in Tsumeb.
MAGNETIC CLOUDS: A SUBJECT OF SPACE WEATHER PREDICTION
Authors: GERANIOS A. , VANDAS M. , ANTONIADOU E. , ZACHAROPOULOU O.
Published: December 2005

Magnetic clouds are ideal objects for solar-terrestrial studies because of their simplicity and their extended time intervals of southward and northward magnetic fields. Magnetic clouds constitute a significant subset of coronal mass ejections with remarkable characteristics in the interplanetary medium and a strong influence on the Earth's magnetosphere, giving rise to geomagnetic storms. The evolution of such a cloud from the neighborhood of the Sun up to the Earth is numerically simulated for two cases, without and with a presence of a faster moving shock front. Its influence on the magnetosphere can be seen by the triggered geomagnetic storm. Therefore, magnetic clouds are an important subject for space weather predictions.
ULYSSES: EXPLORING THE HELIOSPHERE IN FOUR DIMENSIONS
Authors: MARSDEN RICHARD G.
Published: December 2005

Ulysses is the first spacecraft ever to fly over the poles of the sun. Its primary goal is to explore the heliosphere in four dimensions: three spatial dimensions, and time. An overview of some of the recent results from the mission will be presented. Particular emphasis will be given to the changes occurring in the 3-dimensional heliosphere from solar minimum to solar maximum, and their effects on energetic particles and cosmic rays.
THE ANOMALOUS COSMIC RAY COMPONENT: A SHORT SURVEY
Authors: PANASYUK M. I.
Published: December 2005

Cosmic rays in the energy range around ~ 10 MeV/nucl correspond to the so-called "anomalous cosmic rays" (ACR). These particles have low charge states and a high first ionization potential. Below we give a short survey of the current state of experimental results and theoretical models of the ACR component.
ON THE LINK BETWEEN COSMIC RAYS AND TERRESTRIAL CLIMATE
Authors: SHAVIV NIR J.
Published: December 2005

We discuss the problem of cosmic ray diffusion in the Milky Way and show that the spiral arm dynamics gives rise to a ~ 150 Myr periodic modulation of the cosmic ray density in the vicinity of the solar system. We show that these predicted variations are recorded in the exposure ages of Iron meteorites. Given the suspected cosmic ray–climate link, we argue that spiral arm passages are also responsible for the periodic appearance of ice age epochs on Earth. This hypothesis is supported by the clear correlation between ice age epochs and the meteoritic record and also between longer term activity in the Milky Way and glacial activity on Earth.
THEORETICAL AND EXPERIMENTAL STUDIES OF THE 11-YEAR AND 27-DAY VARIATIONS OF THE GALACTIC COSMIC RAYS INTENSITY AND ANISOTROPY
Authors: ALANIA M. V. , GIL A. , ISKRA K. , MODZELEWSKA R. , SILUSZYK M.
Published: December 2005

The changes of the structure in the energy range of the interplanetary magnetic field (IMF) turbulence versus solar activity can be considered as one of the important reasons of the long period (11-year) modulation of galactic cosmic ray (GCR) intensity; the amplitude of the 27-day variation of GCR anisotropy is greater in the qA > 0 periods than in the qA < 0 periods of the solar magnetic cycles in a good correlation with the similar changes of the 27-day variation of GCR intensity.
COSMIC RAY FLUXES IN THE MAXIMUM PHASE OF SOLAR ACTIVITY CYCLES
Authors: BAZILEVSKAYA G. A. , MAKHMUTOV V. S. , STOZHKOV Y. I. , SVIRZHEVSKAYA A. K. , SVIRZHEVSKY N. S.
Published: December 2005

The homogeneous series of primary cosmic ray intensity with energy > 100 MeV is obtained in the long-term balloon measurements of charged particle fluxes performed by Lebedev Physical Institute. Supplementing these data with those of neutron monitors enables us to study the cosmic ray modulation on the wide energy base during more than four solar activity cycles. In the periods of solar activity maximum a transition from cosmic ray decrease to recovery occurs. Changes in fluxes of cosmic rays of lower energy lag behind the changes in fluxes of cosmic rays of higher energy producing an energy hysteresis. After a while cosmic ray fluxes of all energies start to recover. In the cycles 20 and 22 the periods of transition from decline to recovery were shorter than in the cycles 21 and 23. This may be indicative of more complicated passage from the cosmic ray drift in the A > 0 conditions to the drift in the A < 0 conditions than vice versa.
SOLAR NEUTRONS AND INFORMATION CRITERION
Authors: BEISEMBAEV R. U. , DRYN E. A. , KRYAKUNOVA O. N.
Published: December 2005

In the present work is investigated decrease of entropy resulted from the finiteness of the volumes of samples of random variable values. The results of the studies were used for search of direct solar neutrons.
SPACE WEATHER RESEARCH: THE CONNECTION BETWEEN SATELLITE MALFUNCTION DATA AND COSMIC RAY ACTIVITY INDICES
Authors: BELOV A. V. , EROSHENKO E. A. , YANKE V. G. , KRYAKUNOVA O. N. , NIKOLAEVSKIY N. F.
Published: December 2005

Using complex database of satellite malfunctions within the period of 1974–1994 and cosmic ray activity indices, calculated by means of high mountain Alma-Ata neutron monitor data it was shown that malfunction frequency increases during seven days after increase of cosmic ray activity indices. It is significant for high altitude satellite with altitude more than 1000 km.
MAGNETOSPHERIC TRANSMISSION FUNCTION TO SEPARATE NEAR EARTH PRIMARY AND SECONDARY COSMIC RAYS
Authors: BOBIK P. , BOSCHINI M. , GERVASI M. , GRANDI D. , MICELOTTA E. , RANCOITA P. G.
Published: December 2005

The main features of charged particles accessing the Earth magnetosphere have been studied by tracing their trajectories. The reconstruction code has allowed us to perform two simulations of Cosmic Rays (CRs) accessing the AMS detector, one for the 1998 data, and the other for the 2005 (at the moment, the IGRF data are available up to that year). The parameters of the external field model for 2005 have been estimated from the solar conditions in 1982 and 1984, two solar cycles before. The CRs have been assumed to be isotropically impinging on the AMS detector, flying at 400 km altitude with energies reproducing the AMS-01 observed spectrum. The computation of allowed and forbidden primary particle trajectories has enabled us the estimate of the Transmission Function in both periods. A comparison with the overall (primary and secondary) AMS-01 data provides by subtraction the determination of the secondary spectrum.
MODELLING COSMIC RAY ELEMENT SPECTRA AND IONIZATION IN THE IONOSPHERES AND ATMOSPHERES OF TERRESTRIAL AND JOVIAN PLANETS
Authors: BUCHVAROVA M. , VELINOV P. I. Y. , KOBYLINSKI Z.
Published: December 2005

The galactic (GCRs) and anomalous (ACRs) cosmic rays form the lower parts of the planetary ionospheres. For this purpose analytical and numerical spectra for cosmic particles are necessary. Our knowledge of GCR modulation in the solar system was greatly enhanced thanks to the heliospheric missions, Voyagers 1 and 2, Pioneer 10 and Ulysses. In this paper, a new model for the calculation of the GCR and ACR element differential spectra D(E) on the basis of satellite measurements is created. This computed analytical model gives a practical possibility for investigation of experimental data from measurements of GCR and ACR component. The contribution of GCRs and ACRs to the ionization of the atmospheres of outer planets Uranus, Neptune and Pluto increases drastically.
THE GIANT FORBUSH DECREASE IN OCTOBER/NOVEMBER 2003: DATA ANALYSIS FOR THE SOLAR NEUTRON DETECTOR AT GORNERGRAT
Authors: FLÜCKIGER E. O. , BÜTIKOFER R. , DESORGHER L. , MOSER M. R. , MURAKI Y. , MATSUBARA Y. , SAKO T. , TSUCHIYA H. , SAKAI T.
Published: December 2005

In connection with the X17.2 flare on October 28, 2003, a coronal mass ejection was emitted at a high speed directly towards the Earth and caused a dramatic Forbush decrease (Fd) in the count rates of the worldwide network of ground-based cosmic ray detectors. During the initial phase of this Fd the ratios of the two Gornergrat solar neutron telescope particle channels (charged + neutral) and neutral show a step-like increase lasting about three days. This phenomenon is investigated based on Monte Carlo simulations of the cosmic ray cascades in the Earth's atmosphere and of the interactions of the secondary cosmic ray particles with the detector.
HELIUM ISOTOPES IN THE RADIATION BELTS OBTAINED BY HIT ONBOARD TSUBASA
Authors: HAREYAMA M. , ASAEDA M. , FUJII M. , HASEBE N. , KAJIWARA N. , KOBAYASHI M. N. , KODAIRA S. , SAKURAI K. , GOKA T. , KOSHIISHI H. , MATSUMOTO H.
Published: December 2005

The helium isotopes were observed by Heavy Ion Telescope (HIT) onboard the TSUBASA satellite from March, 2002 to September, 2003 in the geostationary transfer orbit. The mass resolution of the HIT instrument is ~ 0.25 amu in energy range 20÷43 MeV/nucleon for helium isotopes. Helium data in the quiet periods were analyzed to obtain the spatial and temporal variation of fluxes of helium isotopes, 3 He and 4 He . From this analysis, the enhancement of 3 He flux as compared with 4 He one in low L-value was found. Both of the helium fluxes strongly fluctuated in their L-distributions in each period.
SOLAR MODULATION OF ATMOSPHERIC COSMIC RADIATION: COMPARISON BETWEEN IN-FLIGHT AND GROUND-LEVEL MEASUREMENTS
Authors: ILES R. H. A. , TAYLOR G. C. , JONES J. B. L.
Published: December 2005

January 2000 saw the start of a collaborative study involving the Mullard Space Science Laboratory, Virgin Atlantic Airways, the Civil Aviation Authority and the National Physical Laboratory in a program to investigate the cosmic radiation exposure to aircrew. The study has been undertaken in view of EU Directive 96/291 (May 2000) which requires the assessment of the level of radiation exposure to aircrew. The project's aims include validation of radiation dose models and evaluation of space weather effects on atmospheric cosmic radiation levels, in particular those effects not accounted for by the models. Ground level measurements are often used as a proxy for variations in cosmic radiation dose levels at aircraft altitudes, especially during Forbush Decreases (FDs) and Solar Energetic Particle (SEP) events. Is this estimation realistic and does the ground level data accurately represent what is happening at altitude? We have investigated the effect of a FD during a flight from Hong Kong to London Heathrow on the 15th July 2000 and compared count rate and dose measurements with simultaneous variations measured at ground level. We have also compared the results with model outputs.
REGISTRATION OF NEUTRONS WITHIN 2 MILLISECONDS AFTER EAS
Authors: JȨDRZEJCZAK K. , KARCZMARCZYK J. , KASZTELAN M. , PETROCHENKOV S. A. , POLAŃSKI A. , SWARZYŃSKI J. , SZABELSKI J. , WIBIG T.
Published: December 2005

We register an excess of signals from neutron detectors within a few milliseconds after passage of EAS front in Łódź EAS array. The most probable explanation is that neutrons are produced in EAS hadron interactions with lead block of muon detector. These neutrons diffuse and are thermalized before the detection. We present experimental data and results of simulations using MCNP code. This "new EAS observable" can be used as inexpensive hadron detector in EAS.
NEW NEUTRON MONITOR STATION IN BAKSAN VALLEY
Authors: KARPOV S. N. , KARPOVA Z. M. , PETKOV V. B. , VASHENYUK E. V. , YANKE V. G.
Published: December 2005

In autumn 2003 a new high-altitude neutron monitor (NM) station located in the Baksan Valley of Northern Caucasus was included in the world-wide network of NMs. The Baksan NM has already registered powerful cosmic ray variations (Forbush–decreases) connected with solar activity in October–November 2003. Since February 2004 the Baksan NM data are accessible via Internet: 〈〉
GLOBAL COSMIC RAY INTENSITY CHANGES, SOLAR ACTIVITY VARIATIONS AND GEOMAGNETIC DISTURBANCES AS NORTH ATLANTIC HURRICANE PRECURSORS
Authors: KAVLAKOV S. P.
Published: December 2005

It was shown that specific changes of the sunspots (SS) number, cosmic ray (CR) intensity and geomagnetic activity indices AP and KP were statistically noticeable in the interval of 30 days before the appearance of a cyclonic rotational system over the North Atlantic, developing gradually in a major hurricane.
THE ATTENUATION LENGTH OF COSMIC RAY IRON IN THE ATMOSPHERE OBTAINED BY TIGER EXPERIMENT
Authors: KODAIRA S. , HAREYAMA M. , HASEBE N. , MIYACHI T. , SAKURAI K. , BINNS W. R. , CUMMINGS J. R. , ISRAEL M. H. , LINK J. T. , RAUCH B. F. , SCOTT L. M. , GEIER S. , MEWALDT R. A. , BARBIER L. M. , MITCHELL J. W. , DE NOLFO G. A. , STREITMATTER R. E. , WADDINGTON C. J.
Published: December 2005

A precise measurement of elemental abundances of galactic cosmic rays from charges Z = 20 to 34 was made by TIGER balloon experiment. Using the various path lengths in the atmosphere between 4 and 16 g/cm2 from the TIGER flight data, we derived the attenuation length of iron nuclei with the energy above 2.5 GeV/n in the atmosphere. As the result, we obtained the attenuation length of 15.5 ± 0.6 g/cm 2 which is consistent with previous results of balloon measurements.
28 OCTOBER 2003 FLARE: HIGH-ENERGY GAMMA EMISSION, TYPE II RADIO EMISSION AND SOLAR PARTICLE OBSERVATIONS
Authors: KUZNETSOV S. N. , KURT V. G. , YU. YUSHKOV B. , MYAGKOVA I. N. , KUDELA K. , BELOV A. V. , CAROUBALOS C. , HILARIS A. , MAVROMICHALAKI H. , MOUSSAS X. , PREKA-PAPADEMA P.
Published: December 2005

The 28 October 2003 flare gave us the unique opportunity to compare the acceleration time of high-energy protons with the escaping time of those particles which have been measured onboard spacecraft and by neutron monitors network as GLE event. High-energy emission time scale and shock wave height and velocity time dependencies were also studied.
USE OF COSMIC RAY MEASUREMENTS TO IDENTIFY THE SECTOR POLARITIES OF THE INTERPLANETARY MAGNETIC FIELD
Authors: LAURENZA MONICA , STORINI MARISA , MORENO GIOVANNI
Published: December 2005

The knowledge of the interplanetary magnetic field sector polarity at the Earth's location is relevant to study many phenomena related to the Space Climatology. We filled the gaps in the daily polarities of the interplanetary magnetic field derived from spacecraft observations by using two sets of ground-based measurements: i) the cosmic ray muon component intensities supplied by the multidirectional Nagoya telescope; ii) the geomagnetic field from the Antarctic Vostok Observatory. We discuss the time variability of the sector polarities inferred from the wavelet technique in the period 1971–1992.
ALERT SYSTEM FOR GROUND LEVEL COSMIC-RAY ENHANCEMENTS PREDICTION AT THE ATHENS NEUTRON MONITOR NETWORK IN REAL-TIME
Authors: MARIATOS G. , MAVROMICHALAKI H. , SARLANIS C. , SOUVATZOGLOU G. , BELOV A. , EROSHENKO E. , YANKE V.
Published: December 2005

The prediction of solar activity is important for various technologies, including operation of low-Earth orbiting satellites, electric power transmission grids, high-frequency radio-communications etc. The Athens Neutron Monitor Network in Real Time, initiated in December 2003, provides data from twenty-one real-time neutron monitor stations, useful for real-time monitoring of cosmic particle fluxes. Recently a program for forecasting the arrival of dangerous middle energy particles on the Earth's surface has started. These program processes the data taken from the Neutron Monitor Network and informs us about the onset of ground level enhancements. In this way enough time to protect technological systems will be given.
COSMIC RAY EVENTS RELATED TO SOLAR ACTIVITY RECORDED AT THE ATHENS NEUTRON MONITOR STATION FOR THE PERIOD 2000–2003
Authors: MAVROMICHALAKI H. , PAPAIOANNOU A. , PETRIDES A. , ASSIMAKOPOULOS B. , SARLANIS C. , SOUVATZOGLOU G.
Published: December 2005

In this work a complete study of 359 solar flares, 111 Halo coronal mass ejections (Halo CMEs) and 45 Partial Halo events occurred from November 2000 to November 2003, is considered. This time period characterized by an unexpected activity of the Sun, was divided into 27-day intervals starting from Bartels Rotation No. 2284 (14.10.2000) to No. 2324 (25.11.2003), generating diagrams of the cosmic ray intensity data recorded at the Athens Neutron Monitor Station. On these qualitative data presented for the first time, a mapping of all available solar and interplanetary events, such as solar flares with importance C, M and X, coronal mass ejections (Halo and Partial) was done. The existence of a connection between solar flares with CMEs and the respective connection to the Forbush effects on yearly and monthly basis are discussed. The role of extreme solar events occurred in March-April 2001 and in October-November 2003 is also considered.
STUDY OF FORBUSH DECREASE EVENT AND ASSOCIATED GEOMAGNETIC FIELD AND COSMIC RAY INTENSITY VARIATION
Authors: MISHRA S. K. , TIWARI D. P. , KAUSHIK S. C.
Published: December 2005

Transient decrease in cosmic ray intensity following by a slow recovery typically lasting for several days is identified as Forbush decrease (Fd) event. As a result the geomagnetic index (Dst) decreased up to 300 nT, indicating a large geomagnetic storm and the percentage Fd decrease has gone to 16% giving rise a cosmic ray storm. Both events coincided with interplanetary conditions. Therefore, a systematic study has been performed to investigate the variation of cosmic ray intensity along with the interplanetary and geomagnetic disturbances. Results indicate a strong relationship between geomagnetic activity and Forbush decrease on short-term basis. Two types of interplanetary transient disturbances, namely magnetic cloud events and bidirectional events are analyzed to study the short-term changes in the solar wind (SW) plasma components as well as in cosmic ray intensity.