Based on combined 3-year data, the IceCube collaboration has reported recently the discovery of a diffuse background of high energy (HE) astrophysical neutrinos with energy above 60 TeV that extends at least up to 3 PeV, in excess (5.7σ significance level) of that produced by cosmic ray (CR) interactions in the atmosphere. The neutrino events did not point back to any identified sources and are...

Based on identifications from the Véron and Quasars.org catalogs, we determine the optical-to-X-ray spectral indices for a sample of 201 BL Lac type objects (BLLs) and search for trends in the distribution of these indices of the sources detected in highenergy bands. We find that EGRET-detected sources are low-energy peaked and that the positional correlation with the arrival directions of ultr...

The origin of the highest-energy cosmic rays remains a mystery. The lack of a high energy cutoff in the cosmic ray spectrum together with an apparently isotropic distribution of arrival directions have strongly constrained most models proposed for the generation of these particles. An overview of the present state of theoretical proposals is presented. Astrophysical accelerators as well as top-...

We have generated UHE cosmic ray showers using the CORSIKA program and the QGSJet hadronic interaction code, and have simulated the response of the HiRes detector to the showers. We included in the simulation the triggering and DAQ characteristics of the detector and the background sky noise. We processed these Monte Carlo events with the same analysis program run on HiRes data. To efficiently ...

Address correspondence to R. D. Jackson, U.S. Water Conservation Lab., 4431 E. Broadway Rd., Phoenix, AZ 85040. Received 16 March 1990; revised 26 June 1990. and gypsum sand. Results are presented in terms of relative bidirectional reflectance factors (BRFs) as a function of view angle at a number of solar zenith angles, nadir BRFs as a function of solar zenith angles, and, for wheat, vegetatio...

Nitrogen is a crucial nutrient affecting plant growth and development and its addition to the soil (as chemical or organic form) influences plant growth characteristics. One experiment was conducted as a factorial based on RCBD with two Chrysanthemum cultivars (‘Fred’ and ‘Angel’( and two N-fertilizer sources [Urea (750 and 1500 g/ha and Nitroxin 7.5 and 15 L/ha] used as fertigation method besi...

The isotropy in the ultra high energy cosmic ray (UHECR) flux observed by Yakutsk and AGASA experiments, is a very strong constraint to production and propagation models alike. Most of the scenarios proposed in the literature should produce a sizable anisotropy as either extragalactic luminous or dark matter is normally associated with the invoked particle sources. We explore the possibility th...

One of the most striking astrophysical phenomena today is the existence of cosmic ray particles with energies in excess of 10 20 eV. While their presence has been confirmed by a number of experiments, it is not clear where and how these particles are accelerated to these energies and how they travel astronomical distances without substantial energy loss. We are entering an exciting new era in c...

Using data from more than ten-years of observations with the Akeno Giant Air Shower Array (AGASA), we published a result that the energy spectrum of ultrahigh energy cosmic rays extends beyond the cutoff energy predicted by Greisen [1], and Zatsepin and Kuzmin [2]. In this paper, we reevaluate the energy determination method used for AGASA events with respect to the lateral distribution of show...