4,916 research outputs found
Systems, interactions and macrotheory
A significant proportion of early HCI research was guided by one very clear vision: that the existing theory base in psychology and cognitive science could be developed to yield engineering tools for use in the interdisciplinary context of HCI design. While interface technologies and heuristic methods for behavioral evaluation have rapidly advanced in both capability and breadth of application, progress toward deeper theory has been modest, and some now believe it to be unnecessary. A case is presented for developing new forms of theory, based around generic “systems of interactors.” An overlapping, layered structure of macro- and microtheories could then serve an explanatory role, and could also bind together contributions from the different disciplines. Novel routes to formalizing and applying such theories provide a host of interesting and tractable problems for future basic research in HCI
Chem-News - An On-Line Pesticide Information Program
Computerization of pesticide information is rapidly becoming a necessity as regulatory agencies expand their activities through enforcement, monitoring, and certification of pesticide applicators. Educational institutions responsible for providing pesticide information and pesticide applicator training for certification must also expand their capabilities for immediate updating and faster retrieval. Two programs at Cornell University, the Chemical-Pesticides Program and the Pesticide Impact Assessment Program (PIAP), are presently involved in developing on-line pesticide information for researchers, extension personnel, and regulatory agencies, as well as for those using pesticides
Submerged in the mainstream? A case study of an immigrant learner in a New Zealand primary classroom
Immigrant children from diverse language backgrounds face not only linguistic challenges when enrolled in mainstream English-medium classrooms, but also difficulties adjusting to an unfamiliar learning community. The culture of primary school classrooms in New Zealand typically reflects conventions across three dimensions: interactional, instructional task performance and cognitive-academic development. All three dimensions are underpinned by the culturally specific discourse conventions involved in language socialisation. New learners may be helped by classmates or their teacher to understand and successfully use these conventions, but left on their own they may sink rather than swim. This is a case study of one Taiwanese 11-year old boy, 'John', who entered a New Zealand primary classroom midway through the school year. John's basic conversational ability was sound, but he did not possess the interactive classroom skills needed to operate in the new culture of learning. Selected from a wider study of the classroom, transcript data from audio-recorded excerpts of John's interactions over several months with his teacher and classmates are interpreted from perspectives derived from sociocultural and language socialisation theories. The article concludes with a brief consideration of the extent to which John constructed, or was constrained from constructing meaningful learning experiences, and suggestions for further research and reflection
‘O sibling, where art thou?’ – a review of avian sibling recognition with respect to the mammalian literature
Avian literature on sibling recognition is rare compared to that developed by mammalian researchers. We compare avian and mammalian research on sibling recognition to identify why avian work is rare, how approaches differ and what avian and mammalian researchers can learn from each other. Three factors: (1) biological differences between birds and mammals, (2) conceptual biases and (3) practical constraints, appear to influence our current understanding. Avian research focuses on colonial species because sibling recognition is considered adaptive where ‘mixing potential’ of dependent young is high; research on a wider range of species, breeding systems and ecological conditions is now needed. Studies of acoustic recognition cues dominate avian literature; other types of cues (e.g. visual, olfactory) deserve further attention. The effect of gender on avian sibling recognition has yet to be investigated; mammalian work shows that gender can have important influences. Most importantly, many researchers assume that birds recognise siblings through ‘direct familiarisation’ (commonly known as associative learning or familiarity); future experiments should also incorporate tests for ‘indirect familiarisation’ (commonly known as phenotype matching). If direct familiarisation proves crucial, avian research should investigate how periods of separation influence sibling discrimination. Mammalian researchers typically interpret sibling recognition in broad functional terms (nepotism, optimal outbreeding); some avian researchers more successfully identify specific and testable adaptive explanations, with greater relevance to natural contexts. We end by reporting exciting discoveries from recent studies of avian sibling recognition that inspire further interest in this topic
Ricci-flat Metrics with U(1) Action and the Dirichlet Boundary-value Problem in Riemannian Quantum Gravity and Isoperimetric Inequalities
The Dirichlet boundary-value problem and isoperimetric inequalities for
positive definite regular solutions of the vacuum Einstein equations are
studied in arbitrary dimensions for the class of metrics with boundaries
admitting a U(1) action. We show that in the case of non-trivial bundles
Taub-Bolt infillings are double-valued whereas Taub-Nut and Eguchi-Hanson
infillings are unique. In the case of trivial bundles, there are two
Schwarzschild infillings in arbitrary dimensions. The condition of whether a
particular type of filling in is possible can be expressed as a limitation on
squashing through a functional dependence on dimension in each case. The case
of the Eguchi-Hanson metric is solved in arbitrary dimension. The Taub-Nut and
the Taub-Bolt are solved in four dimensions and methods for arbitrary dimension
are delineated. For the case of Schwarzschild, analytic formulae for the two
infilling black hole masses in arbitrary dimension have been obtained. This
should facilitate the study of black hole dynamics/thermodynamics in higher
dimensions. We found that all infilling solutions are convex. Thus convexity of
the boundary does not guarantee uniqueness of the infilling. Isoperimetric
inequalities involving the volume of the boundary and the volume of the
infilling solutions are then investigated. In particular, the analogues of
Minkowski's celebrated inequality in flat space are found and discussed
providing insight into the geometric nature of these Ricci-flat spaces.Comment: 40 pages, 3 figure
From vocational training to education: the development of a no-frontiers education policy for Europe?
This article focuses on developments towards an EU educational policy. Education was not included as one of the Community competencies in the Treaty of Rome. The first half of the article analyses the way that the European Court of Justice and the Commission of the European Communities between them managed to develop a series of substantial Community programmes out of Article 128 on vocational training. The second half of the article discusses educational developments in the community following the Treaty on European Union and the Treaty of Amsterdam. Whilst the legal competence of the community now includes education, the author's argument is that the inclusion of an educational competence will not result in further developments to mirror those in the years before the Treaty on Europe</p
Looking for pulsations in HgMn stars through CoRoT lightcurves
HgMn Chemically Peculiar stars are among the quietest stars of the
main-sequence. However, according to theoretical predictions, these stars could
have pulsations related to the very strong overabundances of iron peak
elements, which are produced by atomic diffusion in upper layers. Such
pulsations have never been detected from ground based observations.
Our aim is to search for signatures of pulsations in HgMn stars using the
high quality lightcurves provided by the CoRoT satellite.
We identified three faint stars (V>12), from VLT-GIRAFFE multiobject
spectrograph survey in a field which was planned for observation by CoRoT. They
present the typical characteristics of HgMn stars. They were observed by the
CoRoT satellite during the long run (131 days) which started from the 24th of
October 2007, with the exoplanets CCD's (Additional Programme). In the present
work, we present the analysis of the ground based spectra of these three stars
and the analysis of the corresponding CoRoT lightcurves.
Two of these three HgMn candidates show low amplitude (less than 1.6 mmag)
periodic variations (4.3 and 2.53 days respectively, with harmonics) which are
compatible with periods predicted by theoretical models.Comment: Accepted paper in A&A (7 May 2009
Liver transplantation for glycogen storage disease types I, III, and IV
Glycogen storage disease (GSD) types I, III, and IV can be associated with severe liver disease. The possible development of hepatocellular carcinoma and/or hepatic failure make these GSDs potential candidates for liver transplantation. Early diagnosis and initiation of effective dietary therapy have dramatically improved the outcome of GSD type I by reducing the incidence of liver adenoma and renal insufficiency. Nine type I and 3 type III patients have received liver transplants because of poor metabolic control, multiple liver adenomas, or progressive liver failure. Metabolic abnormalities were corrected in all GSD type I and type III patients, while catch-up growth was reported only in two patients. Whether liver transplantation results in reversal and/or prevention of renal disease remains unclear. Neutropenia persisted in both GSDIb patients post liver transplantation necessitating continuous granulocyte colony stimulating factor treatment. Thirteen GSD type IV patients were liver transplanted because of progressive liver cirrhosis and failure. All but one patient have not had neuromuscular or cardiac complications during follow-up periods for as long as 13 years. Four have died within a week and 5 years after transplantation. Caution should be taken in selecting GSD type IV candidates for liver transplantation because of the variable phenotype, which may include life-limiting extrahepatic manifestations. It remains to be evaluated, whether a genotype-phenotype correlation exists for GSD type IV, which may aid in the decision making. Conclusion Liver transplantation should be considered for patients with glycogen storage disease who have developed liver malignancy or hepatic failure, and for type IV patients with the classical and progressive hepatic form
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Kleptoparasitic melees--modelling food stealing featuring contests with multiple individuals
Kleptoparasitism is the stealing of food by one animal from another. This has been modelled in various ways before, but all previous models have only allowed contests between two individuals. We investigate a model of kleptoparasitism where individuals are allowed to fight in groups of more than two, as often occurs in real populations. We find the equilibrium distribution of the population amongst various behavioural states, conditional upon the strategies played and environmental parameters, and then find evolutionarily stable challenging strategies. We find that there is always at least one ESS, but sometimes there are two or more, and discuss the circumstances when particular ESSs occur, and when there are likely to be multiple ESSs
CXOM31 J004253.1+411422: The first ultra-luminous X-ray transient in M 31
We seek clarification of the nature of X-ray sources detected in M 31. Here
we focus on CXOM31 J004253.1+411422, the brightness of which suggests that it
belongs to the class of ultraluminous X-ray sources. We determine the X-ray
properties of sources detected in the XMM-Newton Chandra monitoring program. We
investigate spectral properties and search for periodic or quasi-periodic
oscillations. A multi-component model is applied to the spectra obtained from
XMM-Newton data to evaluate the relative contributions from thermal and
non-thermal emission. The time dependence of this ratio is evaluated over a
period of forty days. We simultaneously fit data from XMM-Newton EPIC-pn, MOS1
and MOS2 detectors with (non-thermal) powerlaw and (thermal) multicolored
blackbody. The X-ray spectrum is best fit by the combination of a thermal
component with kT ~ 1 keV and a powerlaw component with photon index
approximately 2.6. From combined analysis of Chandra, Swift and XMM-Newton
data, the unabsorbed total luminosity of this source decreases from ~ 3.8 x
10^{39} erg s^{-1} in the first observation to ~ 0.5 x 10^{39} ergs s^{-1} over
a period of three months. The decay closely follows an exponential decline with
a time constant of 32 days. The source spectrum evolves significantly,
exhibiting a faster decline of the thermal component. We do not find evidence
of any significant temporal features in the power density spectrum. The
presence of a thermal component at kT ~ 1 keV in conjunction with a non-thermal
high energy tail, is also consistent with spectral properties of other ULXs in
the "high state". Our analysis indicates that the underlying source of this
first ULX in M~31 is a black hole of mass, M > 13 M_{sun}, accreting near the
Eddington limit, that underwent a transient outburst followed by an exponential
decay reminiscent of transients associated with galactic X-ray novae.Comment: Accepted by Astronomy and Astrophysics. 6 pages, 8 figure
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