10,012 research outputs found
Representation in Westminster in the 1990s : The ghost of Edmund Burke
Why are 'trustee' notions of representation still invoked in the UK House of Commons in the 1990s? In answering this question this article analyses the premises of Burkean theory and the arguments that these premises are of little relevance in the late twentieth century. Despite these dismissals of trusteeship, Burkean ideas are still articulated in the Commons some 200 years after they were first voiced. The idea of trusteeship can prove extremely useful to justify the actions of representatives when those actions conflict with constituency 'opinion', party policy or the wishes of interest groups. Examples of the occasions when Burkean notions have been invoked in the 1990s are provided
The effect of insect herbivory on the growth and fitness of introduced Verbascum thapsus L.
A majority of the plant species that are introduced into new ranges either do not become established, or become naturalized yet do not attain high densities and are thus considered ecologically and economically unproblematic. The factors that limit these relatively “benign” species are not well studied. The biotic resistance hypothesis predicts that herbivores, pathogens and competition reduce growth and reproduction of individual plants and so suppress population growth of non-native species. We explored the effect of insect herbivory and surrounding vegetation on growth and fitness of the non-native biennial plant Verbascum thapsus (common mullein) in Colorado, USA. Mullein is widespread in its introduced North American range, yet is infrequently considered a management concern because populations are often ephemeral and restricted to disturbed sites. To evaluate the impact of insect herbivores on mullein performance, we reduced herbivory using an insecticide treatment and compared sprayed plants to those exposed to ambient levels of herbivory. Reducing herbivory increased survival from rosette to reproduction by 7%, from 70–77%. Of plants that survived, reducing herbivory increased plant area in the first year and plant height, the length of the reproductive spike, and seed set during the second year. Reducing herbivory also had a marked effect on plant fitness, increasing seed set by 50%, from about 48,000 seeds per plant under ambient herbivory to about 98,000 per plant under reduced herbivory. Our findings also highlight that the relationship between herbivory and performance is complex. Among plants exposed to ambient herbivory, we observed a positive relationship between damage and performance, suggesting that, as predicted by the plant vigor hypothesis, insect herbivores choose the largest plants for feeding when their choice is not restricted by insecticide treatment. In contrast to the strong effects of experimentally reduced herbivory, we found that cover of other plants surrounding our focal plants explained relatively little variation in performance outcomes. Overall, we found that herbivore-induced impacts on individual plant performance and seed set are substantial, and thus may help prevent this naturalized species from becoming dominant in undisturbed recipient communities
Mitoxantrone is superior to doxorubicin in a multiagent weekly regimen for patients older than 60 with high-grade lymphoma: results of a BNLI randomized trial of PAdriaCEBO versus PMitCEBO
A prospective, multicenter, randomized trial was undertaken to compare the efficacy and toxicity of adriamycin with mitoxantrone within a 6-drug combination chemotherapy regimen for elderly patients (older than 60 years) with high-grade non-Hodgkin lymphoma (HGL) given for a minimum of 8 weeks. A total of 516 previously untreated patients aged older than 60 years were randomized to receive 1 of 2 anthracycline-containing regimens: adriamycin, 35 mg/m2 intravenously (IV) on day 1 (n = 259), or mitoxantrone, 7 mg/m2 IV on day 1 (n = 257); with prednisolone, 50 mg orally on days 1 to 14; cyclophosphamide, 300 mg/m2 IV on day 1; etoposide, 150 mg/m2 IV on day 1; vincristine, 1.4 mg/m2 IV on day 8; and bleomycin, 10 mg/m2 IV on day 8. Each 2-week cycle was administered for a minimum of 8 weeks in the absence of progression. Forty-three patients were ineligible for analysis. The overall and complete remission rates were 78% and 60% for patients receiving PMitCEBO and 69% and 52% for patients receiving PAdriaCEBO (P = .05, P = .12, respectively). Overall survival was significantly better with PMitCEBO than PAdriaCEBO (P = .0067). However, relapse-free survival was not significantly different (P = .16). At 4 years, 28% of PAdriaCEBO patients and 50% of PMitCEBO patients were alive (P = .0001). Ann Arbor stage III/IV, World Health Organization performance status 2-4, and elevated lactate dehydrogenase negatively influenced overall survival from diagnosis. In conclusion, the PMitCEBO 8-week combination chemotherapy regimen offers high response rates, durable remissions, and acceptable toxicity in elderly patients with HGL
Stylet-Bearing Nematodes Associated with Plants in Iowa Prairies
Native Iowa prairies contained a plant parasitic nematode population which differed markedly in predominant species from populations in cultivated fields. Nematode species and their abundance varied among the five prairies sampled. Aorolaimus was common in most prairies, but is not known in Iowa cultivated soils. Tylenchorhynchus maximus was common in the Kalsow and Sheeder prairies, but was not found in the Cayler and Hayden prairies. Helicotylenchus was common in all prairies, but the species were unevenly distributed
Comment on ``Superconducting PrBa_2Cu_3O_x''
Recently, Zou et al. (Phys. Rev. Lett. 80, 1074, 1998) reported the
observation of bulk superconductivity (SC) for a PrBa_2Cu_3O_x (Pr123) single
crystal grown by the traveling-solvent floating zone (TSFZ) method. The aim of
this Comment is to show the inconsistency of the value of effective magnetic
moment \mu_{eff} reported by Zou et al. (2.92\mu_B) with their magnetic
susceptibility data. The estimation made directly from their data points gives
a considerably smaller value of \mu_{eff}=2.09\mu_B. At the same time the
values of mu_{eff}=2.9\mu_B and 3.1\mu_B were obtained for our Pr123 single
crystals grown by flux method for H||ab-plane and H||c-axis, respectively. This
suggests that Pr occupies only about a half of the RE sites in TSFZ crystal.
The other half of the RE sites is occupied most probably by the nonmagnetic Ba.
Noteworthy, SC with T_c=43 K was observed earlier for
Pr_{0.5}Ca_{0.5}Ba_2Cu_3O_{7-y} thin films. Ba^{2+} has a larger ionic radius
than Pr^{3+} and so the substitution of Ba for Pr could give a natural
explanation not only for the SC in TSFZ Pr123 but also for the elongation of
the distance between the CuO_2 planes observed by Zou et al.Comment: Slightly extended version of Comment accepted to Phys. Rev. Lett.
(v.81, N24, 1998), tentatevely to be publ. 14Dec98. 1 page, REVTex; 1 EPS fi
OAO1657-415 : A `Missing Link' in High Mass X-ray Binaries?
OAO1657-415 is only the seventh eclipsing X-ray pulsar known and therefore
has the potential to yield only the seventh mass of a neutron star in an X-ray
binary. Here we report photometric and spectroscopic observations of candidates
for the optical counterpart to the system and identify a B6V or B5III star as a
possible companion to the neutron star. We measure the observational parameters
of the star and suggest reasons why OAO1657-415 may be unlike other high mass
X-ray binaries.Comment: 5 pages, 5 figures, to be published in 'Evolution of binary and
multiple star systems', proceedings of conference, Bormi
Pedologic Evidence of Two Major Pre-Illinoian Glaciations Near Cleves, Ohio
Author Institution: National Soil Erosion Laboratory, Purdue University ; Department of Agronomy, The Ohio State University ; Department of Geology and Mineralogy, The Ohio State UniversityGlacial derived materials of a pre-Illinoian age rarely are observed in Ohio. In this study a multiple till/outwash exposure was sampled and analyzed pedologically in detail. Based on the weathering of the soils developed in the exposure and other geomorphic relationships, it was concluded that 2 episodes of soil formation had occurred in pre-Illinoian glacial materials. Physical, chemical, mineralogical and micromorphological investigations of the soils formed in these materials demonstrated they had formed under different drainage conditions. Apparently, much of the dissection in the area had occurred after formation of the older soil. The occurrence of 2 glacial sequences of pre-Illinoian age in the Cleves exposure fit the classic count-back sequence of continental glaciations and can be considered as Kansan and Nebraskan in age
Force-detected nuclear magnetic resonance: Recent advances and future challenges
We review recent efforts to detect small numbers of nuclear spins using
magnetic resonance force microscopy. Magnetic resonance force microscopy (MRFM)
is a scanning probe technique that relies on the mechanical measurement of the
weak magnetic force between a microscopic magnet and the magnetic moments in a
sample. Spurred by the recent progress in fabricating ultrasensitive force
detectors, MRFM has rapidly improved its capability over the last decade. Today
it boasts a spin sensitivity that surpasses conventional, inductive nuclear
magnetic resonance detectors by about eight orders of magnitude. In this review
we touch on the origins of this technique and focus on its recent application
to nanoscale nuclear spin ensembles, in particular on the imaging of nanoscale
objects with a three-dimensional (3D) spatial resolution better than 10 nm. We
consider the experimental advances driving this work and highlight the
underlying physical principles and limitations of the method. Finally, we
discuss the challenges that must be met in order to advance the technique
towards single nuclear spin sensitivity -- and perhaps -- to 3D microscopy of
molecules with atomic resolution.Comment: 15 pages & 11 figure
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