743 research outputs found
Grothendieck quasitoposes
A full reflective subcategory E of a presheaf category [C*,Set] is the
category of sheaves for a topology j on C if and only if the reflection
preserves finite limits. Such an E is called a Grothendieck topos. More
generally, one can consider two topologies, j contained in k, and the category
of sheaves for j which are separated for k. The categories E of this form, for
some C, j, and k, are the Grothendieck quasitoposes of the title, previously
studied by Borceux and Pedicchio, and include many examples of categories of
spaces. They also include the category of concrete sheaves for a concrete site.
We show that a full reflective subcategory E of [C*,Set] arises in this way for
some j and k if and only if the reflection preserves monomorphisms as well as
pullbacks over elements of E.Comment: v2: 24 pages, several revisions based on suggestions of referee,
especially the new theorem 5.2; to appear in the Journal of Algebr
Discipline in scottish schools: a comparative survey over time of teachers' and headteachers' perceptions
Circuit breaker prognostics using SF6 data
Control decisions within future energy networks may take account of the health and condition of network assets, pushing condition monitoring within the smart grid remit. In order to support maintenance decisions, this paper proposes a circuit breaker prognostic system, which ranks circuit breakers in order of maintenance priority. By monitoring the SF6 density within a breaker, the system not only predicts the number of days to a critical level, but also incorporates uncertainty by giving upper and lower bounds on the prediction. This prognostic model, which performs linear regression, will be described in this paper, along with case studies demonstrating ranking breakers based on maintenance priority and prognosis of a leaking breaker. Providing an asset manager with this type of information could allow improved management of his/her assets, potentially deferring maintenance to a time when an outage is already scheduled
A Theory of Mind investigation into the appreciation of visual jokes in schizophrenia
BACKGROUND: There is evidence that groups of people with schizophrenia have deficits in Theory of Mind (ToM) capabilities. Previous studies have found these to be linked to psychotic symptoms (or psychotic symptom severity) particularly the presence of delusions and hallucinations. METHODS: A visual joke ToM paradigm was employed where subjects were asked to describe two types of cartoon images, those of a purely Physical nature and those requiring inferences of mental states for interpretation, and to grade them for humour and difficulty. Twenty individuals with a DSM-lV diagnosis of schizophrenia and 20 healthy matched controls were studied. Severity of current psychopathology was measured using the Krawiecka standardized scale of psychotic symptoms. IQ was estimated using the Ammons and Ammons quick test. RESULTS: Individuals with schizophrenia performed significantly worse than controls in both conditions, this difference being most marked in the ToM condition. No relationship was found for poor ToM performance and psychotic positive symptomatology, specifically delusions and hallucinations. CONCLUSION: There was evidence for a compromised ToM capability in the schizophrenia group on this visual joke task. In this instance this could not be linked to particular symptomatology
Understanding and Improving Platinum Anticancer Drugs - Phenanthriplatin
Approximately half of all patients who receive anticancer chemotherapy are treated with a platinum drug. Despite the widespread use of these drugs, the only cure that can be claimed is that of testicular cancer following cisplatin treatment. This article reviews some of our recent work on phenanthriplatin, a cisplatin derivative in which a chloride ion is replaced by phenanthridine, and on one of its analogues, the previously reported pyriplatin. These cationic complexes form monofunctional adducts on DNA that do not significantly distort the duplex, yet efficiently block transcription. Cell-based assays reveal altered cellular uptake properties and a cancer cell-killing profile different from those of established platinum drugs. Mechanistic work, including a crystal structure analysis of platinum-modified DNA in the active site of RNA polymerase II, is discussed herein.National Cancer Institute (U.S.) (Grant CA034992)Misrock Foundation (Postdoctoral Fellowship
Understanding the Clinical Manifestations of 16p11.2 Deletion Syndrome: A Series of Developmental Case Reports in Children
Measuring the difference between actual and reported food intakes in the context of energy balance under laboratory conditions
Acknowledgements The present study was funded by the Food Standards Agency, UK. The Food Standards Agency had no role in the design, analysis or writing of this article. The authors’ responsibilities were as follows: R. J. S., L. M. O’R. and G. W. H. designed the research; L. M. O’R. and Z. F. conducted the research and analysed the data; G. W. H. performed the statistical analyses; P. R. carried out the DLW analysis; R. J. S. had primary responsibility for the final content; R. J. S., L. M. O’R., Z. F., S. W. and M. B. E. L. wrote the paper.Peer reviewedPublisher PD
The overlooked carbon loss due to decayed wood in urban trees
Decayed wood is a common issue in urban trees that deteriorates tree vitality over time, yet its effect on biomass yield therefore stored carbon has been overlooked. We mapped the occurrence and calculated the extent of decayed wood in standing Ulmus procera, Platanus × acerifolia and Corymbia maculata trees. The main stem of 43 trees was measured every metre from the ground to the top by two skilled arborists. All trees were micro-drilled in two to four axes at three points along the stem (0.3 m, 1.3 m, 2.3 m), and at the tree’s live crown. A total of 300 drilling profiles were assessed for decay. Simple linear regression analysis tested the correlation of decayed wood (cm²) against a vitality index and stem DBH. Decay was more frequent and extensive in U. procera, than P. acerifolia and least in C. maculata. Decay was found to be distributed in three different ways in the three different genera. For U. procera, decay did appear to be distributed as a column from the base to the live crown; whereas, decay was distributed as a cone-shape in P. acerifolia and was less likely to be located beyond 2.3 m. In C. maculata decay was distributed as pockets of variable shape and size. The vitality index showed a weak but not significant correlation with the proportion of decayed wood for P. acerifolia and C. maculata but not for U. procera. However, in U. procera, a strong and significant relationship was found between DBH and stem volume loss (R² = 0.8006, P = 0.0046, n = 15). The actual volume loss ranged from 0.17 to 0.75 m³, equivalent to 5%–25% of the stem volume. The carbon loss due to decayed wood for all species ranged between 69–110 kg per tree. Based on model’s calculation, the stem volume of U. procera trees with DBH ≥ 40 cm needs to be discounted by a factor of 13% due to decayed wood regardless of the vitality index. Decayed wood reduces significantly the tree’s standing volume and needs to be considered to better assess the carbon storage potential of urban forests
Oxidative halogenation of cisplatin and carboplatin: synthesis, spectroscopy, and crystal and molecular structures of Pt(IV) prodrugs
A series of Pt(IV) prodrugs has been obtained by oxidative halogenation of either cisplatin or carboplatin. Iodobenzene dichloride is a general reagent that cleanly provides prodrugs bearing axial chlorides without the need to prepare intervening Pt(IV) intermediates or handle chlorine gas. Elemental bromine and iodine afford Pt(IV) compounds as well, although in the case of the iodine-mediated oxidation of carboplatin, an amido-bridged Pt(IV) side product also formed. A detailed analysis of the changes in spectroscopic and structural parameters induced by varying the axial halide is presented. A number of recurring motifs are observed in the solid state structures of these compounds.National Cancer Institute (U.S.) (Grant CA034992
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