183 research outputs found
A Search for Ultra-High Energy Counterparts to Gamma-Ray Bursts
A small air shower array operating over many years has been used to search
for ultra-high energy (UHE) gamma radiation ( TeV) associated with
gamma-ray bursts (GRBs) detected by the BATSE instrument on the Compton
Gamma-Ray Observatory (CGRO). Upper limits for a one minute interval after each
burst are presented for seven GRBs located with zenith angles . A excess over background was observed between 10 and
20 minutes following the onset of a GRB on 11 May 1991. The confidence level
that this is due to a real effect and not a background fluctuation is 99.8\%.
If this effect is real then cosmological models are excluded for this burst
because of absorption of UHE gamma rays by the intergalactic radiation fields.Comment: 4 pages LaTeX with one postscript figure. This version does not use
kluwer.sty and will allow automatic postscript generatio
Urban Foraging and the Relational Ecologies of Belonging
Through a discussion of urban foraging in Seattle, Washington, USA, we examine how people\u27s plant and mushroom harvesting practices in cities are linked to relationships with species, spaces, and ecologies. Bringing a relational approach to political ecology, we discuss the ways that these particular natureâsociety relationships are formed, legitimated, and mobilized in discursive and material ways in urban ecosystems. Engaging closely with and as foragers, we develop an ethnographically grounded ârelational ecologies of belongingâ framework to conceptualize and examine three constituent themes: cultural belonging and identity, belonging and place, and belonging and more-than-human agency. Through this case study, we show the complex ways that urban foraging is underpinned by interconnected and multiple notions of identity, place, mobility, and agency for both humans and more-than-human interlocutors. The focus on relational ecologies of belonging illuminates important challenges for environmental management and public space planning in socioecologically diverse areas. Ultimately, these challenges reflect negotiated visions about how we organize ourselves and live together in cosmopolitan spaces such as cities
Community event sustainability: why donât people volunteer?
Every Saturday, thousands of runners worldwide participate in parkrun â a free five-kilometre run/walk event. Delivery relies on volunteers, and parkrunners are encouraged to volunteer regularly. However, volunteer recruitment is often difficult, and this study aimed to investigate the underpinning reasons for this. Data were collected from 6,749 parkrunners using an online survey, including 860 who had never volunteered. In addition to demographic information and views on incentives, non-volunteers were asked to rate agreement level for 18 statements about not volunteering. Main reasons were preferring to run or walk and not having got round to it. Principal component analysis indicated four underlying factors: inertia, self-interest, lack of knowledge and anxiety. Non-volunteers were younger, slower runners and walkers, less frequent parkrun attendees and had become involved more recently than volunteers. Ease of signing up to volunteer and being unsure of the commitment required were barriers. It is recommended that these two issues are addressed to help volunteer recruitment
Gamma Ray Bursts as Probes of Quantum Gravity
Gamma ray bursts (GRBs) are short and intense pulses of -rays
arriving from random directions in the sky. Several years ago Amelino-Camelia
et al. pointed out that a comparison of time of arrival of photons at different
energies from a GRB could be used to measure (or obtain a limit on) possible
deviations from a constant speed of light at high photons energies. I review
here our current understanding of GRBs and reconsider the possibility of
performing these observations.Comment: Lectures given at the 40th winter school of theretical physics:
Quantum Gravity and Phenomenology, Feb. 2004 Polan
"Author! Author!" : Shakespeare and biography
Original article can be found at: http://www.informaworld.com/smpp/title~content=t714579626~db=all Copyright Informa / Taylor & Francis Group. DOI: 10.1080/17450910902764454Since 1996, not a year has passed without the publication of at least one Shakespeare biography. Yet for many years the place of the author in the practice of understanding literary works has been problematized, and even on occasions eliminated. Criticism reads the âworksâ, and may or may not refer to an author whose âlifeâ contributed to their meaning. Biography seeks the author in the works, the personality that precedes the works and gives them their characteristic shape and meaning. But the form of literary biography addresses the unusual kind of âlifeâ that puts itself into âworksâ, and this is particularly challenging where the âworksâ predominate massively over the salient facts of the âlifeâ. This essay surveys the current terrain of Shakespeare biography, and considers the key questions raised by the medium: can we know anything of Shakespeare's âpersonalityâ from the facts of his life and the survival of his works? What is the status of the kind of speculation that inevitably plays a part in biographical reconstruction? Are biographers in the end telling us as much about themselves as they tell us about Shakespeare?Peer reviewe
Relativistic wave equations for interacting massive particles with arbitrary half-intreger spins
New formulation of relativistic wave equations (RWE) for massive particles
with arbitrary half-integer spins s interacting with external electromagnetic
fields are proposed. They are based on wave functions which are irreducible
tensors of rank n=s-\frac12$) antisymmetric w.r.t. n pairs of indices,
whose components are bispinors. The form of RWE is straightforward and free of
inconsistencies associated with the other approaches to equations describing
interacting higher spin particles
Limits on Fast Radio Bursts and other transient sources at 182 MHz using the Murchison Widefield Array
The Murchison Widefield Array Transients Survey (MWATS):A search for low-frequency variability in a bright Southern hemisphere sample
Planck early results. VIII. The all-sky early Sunyaev-Zeldovich cluster sample
We present the first all-sky sample of galaxy clusters detected blindly by the Planck satellite through the Sunyaev-Zeldovich (SZ) effect from
its six highest frequencies. This early SZ (ESZ) sample is comprised of 189 candidates, which have a high signal-to-noise ratio ranging from 6
to 29. Its high reliability (purity above 95%) is further ensured by an extensive validation process based on Planck internal quality assessments
and by external cross-identification and follow-up observations. Planck provides the first measured SZ signal for about 80% of the 169 previouslyknown
ESZ clusters. Planck furthermore releases 30 new cluster candidates, amongst which 20 meet the ESZ signal-to-noise selection criterion.
At the submission date, twelve of the 20 ESZ candidates were confirmed as new clusters, with eleven confirmed using XMM-Newton snapshot
observations, most of them with disturbed morphologies and low luminosities. The ESZ clusters are mostly at moderate redshifts (86% with z
below 0.3) and span more than a decade in mass, up to the rarest and most massive clusters with masses above 1 Ă 1015 M
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