Multi-Wavelength Observations of Short-Duration Gamma-Ray Bursts: Recent Results

The number of detections as well as significantly deep non-detections of optical/NIR afterglows of Type I (short-duration population) Gamma-Ray Bursts (GRBs) has become large enough that statistically meaningful samples can now be constructed. I present within some recent results on the luminosity distribution of Type I GRB afterglows in comparison to those of Type II GRBs (collapsar population), the issue of the existence of jet breaks in Type I GRB afterglows, and the discovery of dark Type I GRBs.Comment: 10 pages, 3 figures, based on an invited talk, to appear in the proceedings of the Gamma-Ray Burst Symposium 2012- IAA-CSIC - Marbella, editors: Castro-Tirado, A. J., Gorosabel, J. and Park, I. H; v2: accepted, slightly expanded, minor changes after referee repor

Developing organic production in Northern Ireland

This report was presented at the UK Organic Research 2002 Conference. The area of land under organic management in Northern Ireland has increased from 215 ha in January 1998 to 5,000 ha in December 2001. The Minister for the Department of Agriculture and Rural Development (DARD) has set a target for organic farming of 30,000 ha by 2006 and also commissioned an independent study of the strategic needs for developing the Northern Ireland organic sector in 2000. Greenmount College have taken the decision to establish an organic unit to support these DARD initiatives for organic farming and implement key recommendations from the strategy. The College has also initiated a project to gather and analyse data from 45 organic and in-conversion farms over a three-year period. This data will be used to benchmark organic production and assist with conversion and development of the sector

Pseudomodes and the corresponding transformation of the temperature-dependent bath correlation function

In open system approaches with non-Markovian environments, the process of inserting an individual mode (denoted as "pseudomode") into the bath or extracting it from the bath is widely employed. This procedure, however, is typically performed on basis of the spectral density (SD) and does not incorporate temperature. Here, we show how the - temperature-dependent - bath correlation function (BCF) transforms in such a process. We present analytic formulae for the transformed BCF and numerically study the differences between factorizing initial state and global thermal (correlated) initial state of mode and bath, respectively. We find that in the regime of strong coupling of the mode to both system and bath, the differences in the BCFs give rise to pronounced differences in the dynamics of the system.Comment: 12 pages, 4 figure

Multiclass multiserver queueing system in the Halfin-Whitt heavy traffic regime. Asymptotics of the stationary distribution

We consider a heterogeneous queueing system consisting of one large pool of $O(r)$ identical servers, where $r\to\infty$ is the scaling parameter. The arriving customers belong to one of several classes which determines the service times in the distributional sense. The system is heavily loaded in the Halfin-Whitt sense, namely the nominal utilization is $1-a/\sqrt{r}$ where $a>0$ is the spare capacity parameter. Our goal is to obtain bounds on the steady state performance metrics such as the number of customers waiting in the queue $Q^r(\infty)$. While there is a rich literature on deriving process level (transient) scaling limits for such systems, the results for steady state are primarily limited to the single class case. This paper is the first one to address the case of heterogeneity in the steady state regime. Moreover, our results hold for any service policy which does not admit server idling when there are customers waiting in the queue. We assume that the interarrival and service times have exponential distribution, and that customers of each class may abandon while waiting in the queue at a certain rate (which may be zero). We obtain upper bounds of the form $O(\sqrt{r})$ on both $Q^r(\infty)$ and the number of idle servers. The bounds are uniform w.r.t. parameter $r$ and the service policy. In particular, we show that $\limsup_r E \exp(\theta r^{-1/2}Q^r(\infty))<\infty$. Therefore, the sequence $r^{-1/2}Q^r(\infty)$ is tight and has a uniform exponential tail bound. We further consider the system with strictly positive abandonment rates, and show that in this case every weak limit $\hat{Q}(\infty)$ of $r^{-1/2}Q^r(\infty)$ has a sub-Gaussian tail. Namely $E[\exp(\theta (\hat{Q}(\infty))^2)]0$.Comment: 21 page