The deuteron: structure and form factors

A brief review of the history of the discovery of the deuteron in provided. The current status of both experiment and theory for the elastic electron scattering is then presented.Comment: 80 pages, 33 figures, submited to Advances in Nuclear Physic

Consistent phenological shifts in the making of a biodiversity hotspot: the Cape flora

Background The best documented survival responses of organisms to past climate change on short (glacial-interglacial) timescales are distributional shifts. Despite ample evidence on such timescales for local adaptations of populations at specific sites, the long-term impacts of such changes on evolutionary significant units in response to past climatic change have been little documented. Here we use phylogenies to reconstruct changes in distribution and flowering ecology of the Cape flora - South Africa's biodiversity hotspot - through a period of past (Neogene and Quaternary) changes in the seasonality of rainfall over a timescale of several million years. Results Forty-three distributional and phenological shifts consistent with past climatic change occur across the flora, and a comparable number of clades underwent adaptive changes in their flowering phenology (9 clades; half of the clades investigated) as underwent distributional shifts (12 clades; two thirds of the clades investigated). Of extant Cape angiosperm species, 14-41% have been contributed by lineages that show distributional shifts consistent with past climate change, yet a similar proportion (14-55%) arose from lineages that shifted flowering phenology. Conclusions Adaptive changes in ecology at the scale we uncover in the Cape and consistent with past climatic change have not been documented for other floras. Shifts in climate tolerance appear to have been more important in this flora than is currently appreciated, and lineages that underwent such shifts went on to contribute a high proportion of the flora's extant species diversity. That shifts in phenology, on an evolutionary timescale and on such a scale, have not yet been detected for other floras is likely a result of the method used; shifts in flowering phenology cannot be detected in the fossil record

Assessement of tensile strength of graphites by the iosipescu coupon test

Polycrystalline graphites are widely used in the metallurgical, nuclear and aerospace industries. Graphites are particulated composites manufactured with a mixture of coke with pitch, and changes in relative proportions of these materials cause modifications in their mechanical properties. Uniaxial tension tests must be avoided for mechanical characterization in this kind of brittle material, due to difficulties in making the relatively long specimens and premature damages caused during testing set-up. On other types of tests, e.g. bending tests, the specimens are submitted to combined stress states (normal and transverse shear stresses). The Iosipescu shear test, is performed in a beam with two 90° opposite notches machined at the mid-length of the specimens, by applying two forces couples, so that a pure and uniform shear stress state is generated at the cross section between the two notches. When a material is isotropic and brittle, a failure at 45° in relation to the beam long axis can take place, i.e., the tensile normal stress acts parallel to the lateral surface of the notches, controls the failure and the result of the shear test is numerically equivalent to the tensile strength. This work has evaluated a graphite of the type used in rocket nozzles by the Iosipescu test and the resulted stress, ~11 MPa, was found to be equal to the tensile strength. Thus, the tensile strength can be evaluated just by a single and simple experiment, thus avoiding complicated machining of specimen and testing set-up

Interventional radiology virtual simulator for liver biopsy

Purpose Training in Interventional Radiology currently uses the apprenticeship model, where clinical and technical skills of invasive procedures are learnt during practice in patients. This apprenticeship training method is increasingly limited by regulatory restrictions on working hours, concerns over patient risk through trainees’ inexperience and the variable exposure to case mix and emergencies during training. To address this, we have developed a computer-based simulation of visceral needle puncture procedures. Methods A real-time framework has been built that includes: segmentation, physically based modelling, haptics rendering, pseudo-ultrasound generation and the concept of a physical mannequin. It is the result of a close collaboration between different universities, involving computer scientists, clinicians, clinical engineers and occupational psychologists. Results The technical implementation of the framework is a robust and real-time simulation environment combining a physical platform and an immersive computerized virtual environment. The face, content and construct validation have been previously assessed, showing the reliability and effectiveness of this framework, as well as its potential for teaching visceral needle puncture. Conclusion A simulator for ultrasound-guided liver biopsy has been developed. It includes functionalities and metrics extracted from cognitive task analysis. This framework can be useful during training, particularly given the known difficulties in gaining significant practice of core skills in patients

Phytophthora species and oak decline - can a weak competitor cause significant root damage in a nonsterilized acidic forest soil?

Phytophthora species in general, and P. quercina in particular, have been suggested in several studies to be a contributing factor to the problem of oak decline in Europe. Although Phytophthora species are generally regarded as weak competitors, few studies of the pathogenicity of species causing root rot on oaks have hitherto been performed in natural, nonsterilized forest soils. This study describes the effects of seven southern Swedish isolates of P. quercina and one isolate of P. cactorum on root vitality of Quercus robur seedlings grown in a natural, nonsterilized, acidic forest soil. The pathogenicity of P. quercina and P. cactorum were tested using a soil infestation test. The climatic conditions applied were an attempt to simulate summer conditions in southern Sweden. Both species of Phytophthora caused a significant dieback of fine roots, and necrotic lesions on coarser roots, of Q. robur seedlings. Total and live root lengths were significantly lower in infected seedlings than in controls. No significant effects of Phytophthora on above-ground growth or leaf nutrient concentration were found. The results demonstrate that P. quercina and P. cactorum can cause substantial root dieback of seedlings of Q. robur in natural, acidic forest soils in competition with the inhabiting soil microflora under a mesic water regime

Management Impacts on Forest Floor and Soil Organic Carbon in Northern Temperate Forests of the US

<p>Abstract</p> <p>Background</p> <p>The role of forests in the global carbon cycle has been the subject of a great deal of research recently, but the impact of management practices on forest soil dynamics at the stand level has received less attention. This study used six forest management experimental sites in five northern states of the US to investigate the effects of silvicultural treatments (light thinning, heavy thinning, and clearcutting) on forest floor and soil carbon pools.</p> <p>Results</p> <p>No overall trend was found between forest floor carbon stocks in stands subjected to partial or complete harvest treatments. A few sites had larger stocks in control plots, although estimates were often highly variable. Forest floor carbon pools did show a trend of increasing values from southern to northern sites. Surface soil (0-5 cm) organic carbon content and concentration were similar between treated and untreated plots. Overall soil carbon (0-20 cm) pool size was not significantly different from control values in sites treated with partial or complete harvests. No geographic trends were evident for any of the soil properties examined.</p> <p>Conclusions</p> <p>Results indicate that it is unlikely that mineral soil carbon stocks are adversely affected by typical management practices as applied in northern hardwood forests in the US; however, the findings suggest that the forest floor carbon pool may be susceptible to loss.</p

Exclusive Photoproduction of the Cascade (Xi) Hyperons

We report on the first measurement of exclusive Xi-(1321) hyperon photoproduction in gamma p --> K+ K+ Xi- for 3.2 < E(gamma) < 3.9 GeV. The final state is identified by the missing mass in p(gamma,K+ K+)X measured with the CLAS detector at Jefferson Laboratory. We have detected a significant number of the ground-state Xi-(1321)1/2+, and have estimated the total cross section for its production. We have also observed the first excited state Xi-(1530)3/2+. Photoproduction provides a copious source of Xi's. We discuss the possibilities of a search for the recently proposed Xi5-- and Xi5+ pentaquarks.Comment: submitted to Phys. Rev.

Roadless and Low-Traffic Areas as Conservation Targets in Europe

With increasing road encroachment, habitat fragmentation by transport infrastructures has been a serious threat for European biodiversity. Areas with no roads or little traffic (“roadless and low-traffic areas”) represent relatively undisturbed natural habitats and functioning ecosystems. They provide many benefits for biodiversity and human societies (e.g., landscape connectivity, barrier against pests and invasions, ecosystem services). Roadless and low-traffic areas, with a lower level of anthropogenic disturbances, are of special relevance in Europe because of their rarity and, in the context of climate change, because of their contribution to higher resilience and buffering capacity within landscape ecosystems. An analysis of European legal instruments illustrates that, although most laws aimed at protecting targets which are inherent to fragmentation, like connectivity, ecosystem processes or integrity, roadless areas are widely neglected as a legal target. A case study in Germany underlines this finding. Although the Natura 2000 network covers a significant proportion of the country (16%), Natura 2000 sites are highly fragmented and most low-traffic areas (75%) lie unprotected outside this network. This proportion is even higher for the old Federal States (western Germany), where only 20% of the low-traffic areas are protected. We propose that the few remaining roadless and low-traffic areas in Europe should be an important focus of conservation efforts; they should be urgently inventoried, included more explicitly in the law and accounted for in transport and urban planning. Considering them as complementary conservation targets would represent a concrete step towards the strengthening and adaptation of the Natura 2000 network to climate change