Supernovae Shedding Light on Gamma-Ray Bursts

We review the observational status of the Supernova (SN)/Gamma-Ray Burst (GRB) connection. In section 2 we provide a short summary of the observational properties of core-collapse SNe. In sections 3-6 we review the circumstantial evidences and the direct observations that support the existence of a deep connection between the death of massive stars and GRBs. Present data suggest that SNe associated with GRBs form a heterogeneous class of objects including both bright and faint Hypernovae and perhaps also `standard' Ib/c events. In section 7, we provide an empirical estimate of the rate of Hypernovae, for a ``MilkyWay-like'' galaxy, of about $\sim 2.6\times 10^{-4}$ yr$^{-1}$ that may imply the ratio GRB/Hypernovae to be in the range $\sim 0.03-0.7$. In the same framework we find the ratio GRB/SNe-Ibc to be $\sim 0.008\div 0.05$. In section 8 we discuss the possible existence of a lag between the SN explosion and the associated gamma-ray event. In the few SN/GRB associations so far discovered the SN explosions and GRB events appear to go off simultaneously. In section 9 we present the conclusions and highlight the open problems that Swift hopefully will allow us to solve.Comment: 20 pages, 13 figures, invited review at the 4th Workshop Gamma-Ray Bursts in the Afterglow Era, Rome,18-22 October 2004. Editors: L. Piro, L. Amati, S. Covino, and B. Gendre. Il Nuovo Cimento, in pres

Three-Loop Calculation of the Anyonic Full Cluster Expansion

We calculate the perturbative correction to every cluster coefficient of a gas of anyons through second order in the anyon coupling constant, as described by Chern-Simons field theory.Comment: 10 pages, PlainTex with macro 'manumac', include

How to improve business process performance using process mining

Due to the increased use of information systems by organizations to support process execution, detailed information on the implementation of business processes is being recorded. This fact enables using process mining projects as a powerful tool for improving performance. Process Mining is a relative young research discipline that sits between data science on the one hand and process modelling and analysis on the other hand. Process mining allows gaining knowledge of the organization’s actual business processes by extracting data from existing information systems mediums such as event logs, transaction logs etc. The purpose of this presentation is to demonstrate how a process for conducting process mining projects was designed, developed and applied in some organizational units. The process was implemented through nine research steps, inspired by the V-model, where elements on the right-hand side aim to answer questions presented in steps on the left-hand side. In the first two steps, the research problem and the research objectives were defined. A literature review was performed in step 3. In the fourth step, requirements for the process were identified and implemented. In step 5, a running example was carried out to test the process. Verification and validation of the process were performed in step 6 and step 7. Step 8 covered the discussion of results. The last step concludes the research, including checking if the research problem was solved. Organizations seeking for performance improvement can now benefit of a process that explicitly states which process mining tools, techniques and algorithms to be used in process mining projects

On Core Collapse Supernovae in Normal and in Seyfert Galaxies

This paper estimates the relative frequency of different types of core-collapse supernovae, in terms of the ratio f between the number of type Ib--Ic and of type II supernovae. We estimate f independently for all normal and Seyfert galaxies whose radial velocity is <=14000 km/s, and which had at least one supernova event recorded in the Asiago catalogue from January 1986 to August 2000. We find that the ratio f is approx. 0.23+/-0.05 in normal galaxies. This value is consistent with constant star formation rate and with a Salpeter Initial Mass Function and average binary rate approx. 50 %. On the contrary, Seyfert galaxies exceed the ratio f in normal galaxies by a factor approx. 4 at a confidence level >= 2 sigma. A caveat is that the numbers for Seyferts are still small (6 type Ib-Ic and 6 type II supernovae discovered as yet). Assumed real, this excess of type Ib and Ic with respect to type II supernovae, may indicate a burst of star formation of young age (<= 20 Myr), a high incidence of binary systems in the inner regions (r <= 0.4 R25) of Seyfert galaxies, or a top-loaded mass function.Comment: Accepted for Publication in MNRA

Comprehensive learning incorporating Ako: A tertiary education approach at Wintec

This article outlines the design and implementation of a scenario-based approach to teaching and learning in tertiary education, inspired from Ako, adopted at the Waikato Institute of Technology (Wintec). This learning approach, titled ‘Comprehensive Learning (CL)’, aligns with the holistic objective of enabling students with an active, flexible, personalised, authentic and practical approach to learning that builds upon students’ interests and experiences. The article explains the motivation and the process used in creating and applying this approach to teach some of the IT and Business modules. The main reason to implement this approach is to encourage/enable critical thinking while learning in a continuous and personalised manner. CL allows students to specialize in a context of their choice, which in turn induces learning. In addition, students are less motivated to plagiarize due to the unique nature of their scenarios, and inherent safeguards present within the approach

Modelling tri-bimaximal neutrino mixing

We model tri-bimaximal lepton mixing from first principles in a way that avoids the problem of the vacuum alignment characteristic of such models. This is achieved by using a softly broken A4 symmetry realized with an isotriplet fermion, also triplet under A4. No scalar A4-triplet is introduced. This represents one possible realization of general schemes characterized by the minimal set of either three or five physical parameters. In the three parameter versions mee vanishes, while in the five parameter schemes the absolute scale of neutrino mass, although not predicted, is related to the two Majorana phases. The model realization we discuss is potentially testable at the LHC through the peculiar leptonic decay patterns of the fermionic and scalar triplets.Comment: some changing, reference adde