Search for shadowing of primary cosmic radiation by the moon at TeV energies     

D. Pomarde  P. J. Boyle  M. Urban  H. M. Badran  L. Behr  M. T. Brunetti  D. J. Fegan  T. C. Weekes 《Astroparticle Physics》2001,14(4)

The antimatter research through the earth moon ion spectrometer (ARTEMIS) experiment is described in terms of searching for the moon's shadow in the primary cosmic radiation at TeV energies. Observations were made using the Whipple 10 m Imaging Atmospheric erenkov Telescope, in conjunction with a special optical filter to suppress unwanted moonlight. Monte Carlo simulations were used to predict that the magnitude of shadowing based on a pure proton beam would be 1% of the cosmic ray background. Observations and event classification are discussed, and results of a search for shadowing based on both protons and antiprotons are presented. Atmospheric fluctuations giving rise to non-statistical event rates constituted a limiting factor to the sensitivity of the shadow search as they rivaled or exceeded statistical errors. It is demonstrated that the experiment does not have sufficient sensitivity to moon shadowing which would allow a search for an antimatter component in the primary cosmic ray flux at the percent level. Possible future improvements of the technique are discussed.  相似文献   

Particle reacceleration in the Coma cluster: radio properties and hard X-ray emission   总被引：1，自引：0，他引：1  

G. Brunetti  G. Setti  L. Feretti  G. Giovannini 《Monthly notices of the Royal Astronomical Society》2001,320(3):365-378

The radio spectral index map of the Coma halo shows a progressive steepening of the spectral index with increasing radius. Such a steepening cannot be simply justified by models involving continuous injection of fresh particles in the Coma halo or by models involving diffusion of fresh electrons from the central regions.
We propose a two-phase model in which the relativistic electrons injected in the Coma cluster by some processes (starbursts, AGNs, shocks, turbulence) during a first phase in the past are systematically reaccelerated during a second phase for a relatively long time (∼1 Gyr) up to the present time. We show that for reacceleration time-scales of ∼0.1 Gyr this hypothesis can well account for the radio properties of Coma C. For the same range of parameters which explain Coma C we have calculated the expected fluxes from the inverse Compton scattering of the Cosmic Microwave Background (CMB) photons, finding that the hard X-ray tail discovered by BeppoSAX may be accounted for by the stronger reacceleration allowed by the model.
The possibility of extending the main model assumptions and findings to the case of the other radio haloes is also discussed, the basic predictions being consistent with the observations.  相似文献   

New scaling relations in cluster radio haloes and the re-acceleration model     

R. Cassano  G. Brunetti  G. Setti  F. Govoni  K. Dolag 《Monthly notices of the Royal Astronomical Society》2007,378(4):1565-1574

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Mineral species control of aluminum solubility in sulfate-rich acidic waters     

Adele M. Jones 《Geochimica et cosmochimica acta》2011,75(4):965-139

The identification of the mineral species controlling the solubility of Al in acidic waters rich in sulfate has presented researchers with several challenges. One of the particular challenges is that the mineral species may be amorphous by X-ray diffraction. The difficulty in discerning between adsorbed or structural sulfate is a further complication. Numerous studies have employed theoretical calculations to determine the Al mineral species forming in acid sulfate soil environments. The vast majority of these studies indicate the formation of a mineral species matching the stoichiometry of jurbanite, Al(OH)SO₄·5H₂O. Much debate, however, exists as to the reality of jurbanite forming in natural environments, particularly in view of its apparent rare occurrence. In this work the use of Al, S and O K-edge XANES spectroscopy, in combination with elemental composition analyses of groundwater precipitates and a theoretical analysis of soluble Al concentrations ranging from pH 3.5 to 7, were employed to determine the mineral species controlling the solubility of Al draining from acid sulfate soils into Blacks Drain in north-eastern New South Wales, Australia. The results indicate that a mixture of amorphous Al hydroxide (Al(OH)₃) and basaluminite (Al₄(SO₄)(OH)₁₀·5H₂O) was forming. The use of XANES spectroscopy is particularly useful as it provides insight into the nature of the bond between sulfate and Al, and confirms the presence of basaluminite. This counters the possibility that an Al hydroxide species, with appreciable amounts of adsorbed sulfate, is forming within these groundwaters.Below approximately pH 4.5, prior to precipitation of this amorphous Al(OH)₃/basaluminite mixture, our studies indicate that the Al³⁺ activity of these acidic sulfate-rich waters is limited by the availability of dissolved Al from exchangeable and amorphous/poorly crystalline mineral species within adjacent soils. Further evidence suggests the Al³⁺ activity below pH 4.5 is then further controlled by dilution with either rainwater or pH 6-8 buffered estuarine water, and not a notional Al(OH)SO₄ mineral species.  相似文献   

Quality and origin of mountain food products: the new European label as a strategy for sustainable development     

Deborah BENTIVOGLIO  Sara SAVINI  Adele FINCO  Giorgia BUCCI  Emanuele BOSELLI 《山地科学学报》2019,(2)

Mountain farming provides high-quality food products due to the peculiar characteristics of the raw materials combined with traditional processing conditions. However, these products and their intrinsic characteristics are not clearly recognized by consumers on the market. Nowadays, Protected Designation of Origin(PDO), Protected Geographical Indication(PGI) and Traditional Specialities Guaranteed(TSG) certifications include products originating in mountain areas, even if a large part of mountain foodstuff is not protected by these certifications and foods not made in mountain areas are often labeled as ―mountain food products‖. For this reason, the European Union has set a specific Regulation in 2012 to recognize and protect mountain food and to make the consumers safer about the origin information. The objective of this paper is twofold: firstly, it presents the recent aspects related to European legislation of mountain food product; secondly, it aims at reviewing the main features of nutritional quality and technology of dairy and meat products, as the most widespread mountain food products, and the main protocols used to evaluate the authenticity of these food products. The promotion of mountain food product through a specific label and the use of tracing methods, which are able to verify the authenticity of the origin of these products, may play a pivotal role in increasing the consumer‘s loyalty towards these products and could be a way to boost a sustainable development of these economically marginal rural areas. However, the analytical protocols developed so far(stable isotopes, macro and microelements, radionuclides, spectroscopic, molecular techniques, volatile substances profile, terpenes) are in many cases still at the experimental level due to the extreme variability of the mountain origin of the products to be tested.  相似文献   

Shock waves in Eulerian cosmological simulations: main properties and acceleration of cosmic rays     

F. Vazza  G. Brunetti  C. Gheller 《Monthly notices of the Royal Astronomical Society》2009,395(3):1333-1354

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Dissociation kinetics of Fe(III)- and Al(III)-natural organic matter complexes at pH 6.0 and 8.0 and 25 °C     

Adele M. Jones 《Geochimica et cosmochimica acta》2009,73(10):2875-10090

The rate at which iron- and aluminium-natural organic matter (NOM) complexes dissociate plays a critical role in the transport of these elements given the readiness with which they hydrolyse and precipitate. Despite this, there have only been a few reliable studies on the dissociation kinetics of these complexes suggesting half-times of some hours for the dissociation of Fe(III) and Al(III) from a strongly binding component of NOM. First-order dissociation rate constants are re-evaluated here at pH 6.0 and 8.0 and 25 °C using both cation exchange resin and competing ligand methods for Fe(III) and a cation exchange resin method only for Al(III) complexes. Both methods provide similar results at a particular pH with a two-ligand model accounting satisfactorily for the dissociation kinetics results obtained. For Fe(III), half-times on the order of 6-7 h were obtained for dissociation of the strong component and 4-5 min for dissociation of the weak component. For aluminium, the half-times were on the order of 1.5 h and 1-2 min for the strong and weak components, respectively. Overall, Fe(III) complexes with NOM are more stable than analogous complexes with Al(III), implying Fe(III) may be transported further from its source upon dilution and dispersion.  相似文献   

Definition and performance of a threshold-based regional early warning model for rainfall-induced landslides     

Luca Piciullo  Stefano Luigi Gariano  Massimo Melillo  Maria Teresa Brunetti  Silvia Peruccacci  Fausto Guzzetti  Michele Calvello 《Landslides》2017,14(3):995-1008

A process chain for the definition and the performance assessment of an operational regional warning model for rainfall-induced landslides, based on rainfall thresholds, is proposed and tested in a landslide-prone area in the Campania region, southern Italy. A database of 96 shallow landslides triggered by rainfall in the period 2003–2010 and rainfall data gathered from 58 rain gauges are used. First, a set of rainfall threshold equations are defined applying a well-known frequentist method to all the reconstructed rainfall conditions responsible for the documented landslides in the area of analysis. Several thresholds at different exceedance probabilities (percentiles) are evaluated, and nine different percentile combinations are selected for the activation of three warning levels. Subsequently, for each combination, the issuing of warning levels is computed by comparing, over time, the measured rainfall with the pre-defined warning level thresholds. Finally, the optimal percentile combination to be employed in the regional early warning system, i.e. the one providing the best model performance in terms of success and error indicators, is selected employing the “event, duration matrix, performance” (EDuMaP) method.  相似文献   

Robust smooth magneto tell uric transfer functions   总被引：3，自引：0，他引：3  

Jimmy C. Larsen    Randall L. Mackie    Adele Manzella    Adolfo Fiordelisi  Shirley Rieven 《Geophysical Journal International》1996,124(3):801-819

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The distribution of particulate matter in the Atlantic Ocean     

Peter G. Brewer  Derek W. Spencer  Pierre E. Biscaye  Adele Hanley  Peter L. Sachs  Clarence L. Smith  Susan Kadar  Janet Fredericks 《Earth and Planetary Science Letters》1976,32(2):393-402

We have determined the dry weight of suspended particulate matter in seawater in a section through the western Atlantic Ocean from 75°N to 52°S. The concentrations, operationally defined as that weight retained on 0.6-μm and 0.4-μm pore size Nuclepore filters, contained in 1 kg of seawater, range from 5 to 300 μg/kg and show readily explainable regional features. High concentrations are found in surface waters and in association with radpidly moving bottom waters in the Denmark Straits overflow and in Antarctic bottom waters to 15°S. Low concentrations, <12 μg/kg, characterize the mid-water regions of the sub-tropical gyres. High concentrations are seen in sinking Labrador Sea water and in a plume extending at least a kilometer off the bottom at 35°N–40°N where the cruise track intersects the North Atlantic gyre. It is doubtful whether this important phenomenon could be observed by any means other than through particulate observations, either optical or gravimetric, and this provides a unique insight into the scale of vertical turbulent processes.  相似文献