697 research outputs found
Sightings of New Zealand Fairy Tern Sternula nereis davisae in the Kaipara Harbour following nest failure
The cleaning of burned and contaminated archaeological maize prior to 87Sr/86Sr analysis
Accurate trace-metal and strontium-isotope analyses of archaeological corn cobs require that metal contaminants be removed prior to chemical analysis. Archaeological cobs are often coated with construction debris, dust, or soilwhich contains mineral particles. In addition, most archaeological cobs are partially or completely burned and the burned parts incorporate mineral debris in their hardened residual structures. Unburned cobs are weak ion exchangers and most metals within a cob are not firmly bound to cob organic matter; therefore, immersing cobs in acids and rinsing them in deionized water to remove mineral contaminants may result in the undesirable loss of metals, including strontium, from the cob.
In this paper we show that some cob metal-pair ratios are not substantially changed when the cob is ââcleanedââ with deionized water, if the water-cob contact time does not exceed five minutes. Additionally, we introduce a method for eliminating mineral contaminants in both burned and unburned cobs, thus rendering them acceptable for strontium-isotope analysis. However, the decontamination procedure results in the rapid non-stoichiometric leaching of trace metals from the unburned cobs and it is possible that most metals will be extracted from the cobs during the lengthy decontamination process. Trace metals, in particular Al and Ca, should be analyzed in order to determine the presence and level of mineral contamination after cleaning
Constraining properties of the black hole population using LISA
LISA should detect gravitational waves from tens to hundreds of systems
containing black holes with mass in the range from 10 thousand to 10 million
solar masses. Black holes in this mass range are not well constrained by
current electromagnetic observations, so LISA could significantly enhance our
understanding of the astrophysics of such systems. In this paper, we describe a
framework for combining LISA observations to make statements about massive
black hole populations. We summarise the constraints that LISA observations of
extreme-mass-ratio inspirals might be able to place on the mass function of
black holes in the LISA range. We also describe how LISA observations can be
used to choose between different models for the hierarchical growth of
structure in the early Universe. We consider four models that differ in their
prescription for the initial mass distribution of black hole seeds, and in the
efficiency of accretion onto the black holes. We show that with as little as 3
months of LISA data we can clearly distinguish between these models, even under
relatively pessimistic assumptions about the performance of the detector and
our knowledge of the gravitational waveforms.Comment: 12 pages, 3 figures, submitted to Class. Quantum Grav. for
proceedings of 8th LISA Symposium; v2 minor changes for consistency with
accepted versio
Outcome of children with resistant and relapsed Hodgkin's disease.
During the period 1974-89, 169 children with Hodgkin's disease were treated in the Paediatric Oncology Units of the Royal Marsden and St Bartholomew's Hospitals. The overall actuarial survival for the whole group was 81% at 10 years. Thirty-five of the 169 children either did not achieve a complete remission or subsequently relapsed. The estimated actuarial survival from initial relapse or failure of primary treatment was 60% at 5 years and 45% at 10 years. Over half of the patients requiring salvage therapy had declared themselves within 2 years and only 3 relapses occurred more than 3 years from diagnosis. Very few patients remain disease free long term after failure of primary and initial salvage therapy. Patients relapsing within a year of diagnosis or not achieving a complete response to primary therapy and those with disseminated relapse had a poor response to salvage therapy. A significant subgroup of patients had prolonged survival despite multiple relapses. Neither initial histology nor stage affected survival from relapse although numbers in each subgroup were small
Exploring the quotidian in young children's lives at home
The challenges of conducting research in the home, especially with preschool children, mean that the role of the home as a site for research is often overlooked by educationalists. Our repeat visits to fourteen families that included a three- or four-year-old child over more than a year as part of our study âYoung Children Learning with Toys and Technology at Homeâ enabled us to develop research relationships that resulted in a 100 percent retention rate. We summarize the ecocultural framework that informed the design of our study and describe two methods for collecting data (âtoy toursâ and âmobile phone diariesâ) that highlight issues relating to the rules of engagement when conducting research that generates insights into childrenâs everyday lives at home
Probing seed black holes using future gravitational-wave detectors
Identifying the properties of the first generation of seeds of massive black
holes is key to understanding the merger history and growth of galaxies.
Mergers between ~100 solar mass seed black holes generate gravitational waves
in the 0.1-10Hz band that lies between the sensitivity bands of existing
ground-based detectors and the planned space-based gravitational wave detector,
the Laser Interferometer Space Antenna (LISA). However, there are proposals for
more advanced detectors that will bridge this gap, including the third
generation ground-based Einstein Telescope and the space-based detector DECIGO.
In this paper we demonstrate that such future detectors should be able to
detect gravitational waves produced by the coalescence of the first generation
of light seed black-hole binaries and provide information on the evolution of
structure in that era. These observations will be complementary to those that
LISA will make of subsequent mergers between more massive black holes. We
compute the sensitivity of various future detectors to seed black-hole mergers,
and use this to explore the number and properties of the events that each
detector might see in three years of observation. For this calculation, we make
use of galaxy merger trees and two different seed black hole mass distributions
in order to construct the astrophysical population of events. We also consider
the accuracy with which networks of future ground-based detectors will be able
to measure the parameters of seed black hole mergers, in particular the
luminosity distance to the source. We show that distance precisions of ~30% are
achievable, which should be sufficient for us to say with confidence that the
sources are at high redshift.Comment: 14 pages, 6 figures, 2 tables, accepted for proceedings of 13th GWDAW
meetin
Is complexity leadership theory complex enough? A critical appraisal, some modifications and suggestions for further research
Scholars are increasingly seeking to develop theories that explain the underlying processes whereby leadership is enacted. This shifts attention away from the actions of âheroicâ individuals and towards the social contexts in which people with greater or lesser power influence each other. A number of researchers have embraced complexity theory, with its emphasis on non-linearity and unpredictability. However, some complexity scholars still depict the theory and practice of leadership in relatively non-complex terms. They continue to assume that leaders can exercise rational, extensive and purposeful influence on other actors to a greater extent than is possible. In effect, they offer a theory of complex organizations led by non-complex leaders who establish themselves by relatively non-complex means. This testifies to the enduring power of âheroicâ images of leader agency. Without greater care, the terminology offered by complexity leadership theory could become little more than a new mask for old theories that legitimize imbalanced power relationships in the workplace. This paper explores how these problems are evident in complexity leadership theory, suggests that communication and process perspectives help to overcome them, and outlines an agenda for further research on these issues
CrashEd â A live immersive, learning experience embedding STEM subjects in a realistic, interactive crime scene
Interactive experiences are rapidly becoming popular via the surge of âescape roomsâ; part game and part theatre, the âescapeâ experience is exploding globally, having gone from zero offered at the outset of 2010 to at least 2800 different experiences available worldwide today. CrashEd is an interactive learning experience that parallels many of the attractions of an escape room â it incorporates a staged, realistic âcrime sceneâ and invites participants to work together to gather forensic evidence and question a witness in order to solve a crime, all whilst competing against a ticking clock. An animation can enhance reality and engage with cognitive processes to help learning; in CrashEd, it is the last piece of the jigsaw that consolidates the studentsâ incremental acquisition of knowledge to tie together the pieces of evidence, identify a suspect and ultimately solve the crime. This article presents the background to CrashEd and an overview of how a timely placed animation at the end of an educational experience can enhance learning. The lessons learned, from delivering bespoke versions of the experience to different demographic groups, are discussed. The article will consider the successes and challenges raised by the collaborative project, future developments and potential wider implications of the development of CrashEd
Daily antibiotic cost of nosocomial infections in a Turkish university hospital
BACKGROUND: Many studies associated nosocomial infections with increased hospital costs due to extra days in hospital, staff time, extra investigations and drug treatment. The cost of antibiotic treatment for these infections represents a significant part of hospital expenditure. This prospective observational study was designed to determine the daily antibiotic cost of nosocomial infections per infected adult patient in Akdeniz University Hospital. METHODS: All adult patients admitted to the ICUs between January 1, 2000, and June 30, 2003 who had only one nosocomial infection during their stay were included in the study. Infection sites and pathogens, antimicrobial treatment of patient and it's cost were recorded. Daily antibiotic costs were calculated per infected patient. RESULTS: Among the 8460 study patients, 817 (16.6%) developed 1407 episodes of nosocomial infection. Two hundred thirty three (2.7%) presented with only one nosocomial infection. Mean daily antibiotic cost was 99.02 for pneumonia, 94.31 for surgical site infection, 162.35 for the other infections per patient. The treatment of Pseudomonas aeruginosa infections was the most expensive infection treated. Piperacillin-tazobactam and amikacin were the most prescribed antibiotics, and meropenem was the most expensive drug for treatment of the nosocomial infections in the ICU. CONCLUSIONS: Daily antibiotic cost of nosocomial infections is an important part of extra costs that should be reduced providing rational antibiotic usage in hospitals
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