309 research outputs found
Exoplanet Terra Incognita
Exoplanet surface imaging, cartography and the search for exolife are the
next frontiers of planetology and astrophysics. Here we present an over-view of
ideas and techniques to resolve albedo features on exoplanetary surfaces.
Albedo maps obtained in various spectral bands (similar to true-colour images)
may reveal exoplanet terrains, geological history, life colonies, and even
artificial structures of advanced civilizations.Comment: 16 pages, 6 figures, Planetary Cartograph
Measurement of the proton and deuteron structure functions, F2p and F2d, and of the ratio sigma(L)/sigma(T)
The muon-proton and muon-deuteron inclusive deep inelastic scattering cross
sections were measured in the kinematic range 0.002 < x < 0.60 and 0.5 < Q2 <
75 GeV2 at incident muon energies of 90, 120, 200 and 280 GeV. These results
are based on the full data set collected by the New Muon Collaboration,
including the data taken with a small angle trigger. The extracted values of
the structure functions F2p and F2d are in good agreement with those from other
experiments. The data cover a sufficient range of y to allow the determination
of the ratio of the longitudinally to transversely polarised virtual photon
absorption cross sections, R= sigma(L)/sigma(T), for 0.002 < x < 0.12 . The
values of R are compatible with a perturbative QCD prediction; they agree with
earlier measurements and extend to smaller x.Comment: In this replacement the erroneously quoted R values in tables 3-6 for
x>0.12, and R1990 values in tables 5-6 for all x, have been corrected, and
the cross sections in tables 3-4 have been adapted. Everything else,
including the structure functions F2, remained unchanged. 22 pages, LateX,
including figures, with two .sty files, and three separate f2tab.tex files
for the F2-tables. Accepted for publication in Nucl.Phys.B 199
Lesson learned during the designing and construction phases of the ORC-plus thermal energy storage system of 20 MWH
A limitation to the expansion of medium sized Concentrating Solar Power (CSP) plants is represented by the lack of technical solutions of Thermal Energy Storage (TES) systems specialized for this size of CSP plants and validated in a relevant industrial environment. In order to make the medium sized CSP systems more competitive than PV systems, the TES system has to allow the operators of the solar power plant to adjust the electricity production for matching consumer demand, so enabling the sale of electricity during peak demand periods for boosting plant revenues. At the same time, there is the need of lowering the TES system weight in the capital costs of the overall system. The ORC-PLUS (Organic Rankine Cycle - Prototype Link to Storage Unit) Project aims to realize a demonstrator of a TES system optimized for a medium sized CSP plant coupled with an ORC (Organic Rankine Cycle) turbine of 1 MWe. In this paper, the difficulties encountered during the manufacturing and commissioning operations of the TES system and their potential impact on capital costs will be reported
Queen mandibular pheromone: questions that remain to be resolved
The discovery of ‘queen substance’, and the subsequent identification and synthesis of keycomponents of queen mandibular pheromone, has been of significant importance to beekeepers and to thebeekeeping industry. Fifty years on, there is greater appreciation of the importance and complexity of queenpheromones, but many mysteries remain about the mechanisms through which pheromones operate. Thediscovery of sex pheromone communication in moths occurred within the same time period, but in this case,intense pressure to find better means of pest management resulted in a remarkable focusing of research activityon understanding pheromone detection mechanisms and the central processing of pheromone signals in themoth. We can benefit from this work and here, studies on moths are used to highlight some of the gaps in ourknowledge of pheromone communication in bees. A better understanding of pheromone communication inhoney bees promises improved strategies for the successful management of these extraordinary animals
Post-mortem assessment in vascular dementia: advances and aspirations.
BACKGROUND: Cerebrovascular lesions are a frequent finding in the elderly population. However, the impact of these lesions on cognitive performance, the prevalence of vascular dementia, and the pathophysiology behind characteristic in vivo imaging findings are subject to controversy. Moreover, there are no standardised criteria for the neuropathological assessment of cerebrovascular disease or its related lesions in human post-mortem brains, and conventional histological techniques may indeed be insufficient to fully reflect the consequences of cerebrovascular disease. DISCUSSION: Here, we review and discuss both the neuropathological and in vivo imaging characteristics of cerebrovascular disease, prevalence rates of vascular dementia, and clinico-pathological correlations. We also discuss the frequent comorbidity of cerebrovascular pathology and Alzheimer's disease pathology, as well as the difficult and controversial issue of clinically differentiating between Alzheimer's disease, vascular dementia and mixed Alzheimer's disease/vascular dementia. Finally, we consider additional novel approaches to complement and enhance current post-mortem assessment of cerebral human tissue. CONCLUSION: Elucidation of the pathophysiology of cerebrovascular disease, clarification of characteristic findings of in vivo imaging and knowledge about the impact of combined pathologies are needed to improve the diagnostic accuracy of clinical diagnoses
Mannose-Binding Lectin Deficiency Is Associated With Smaller Infarction Size and Favorable Outcome in Ischemic Stroke Patients
BACKGROUND: The Mannose-binding lectin (MBL) pathway of complement plays a pivotal role in the pathogenesis of ischemia/reperfusion (I/R) injury after experimental ischemic stroke. As comparable data in human ischemic stroke are limited, we investigated in more detail the association of MBL deficiency with infarction volume and functional outcome in a large cohort of patients receiving intravenous thrombolysis or conservative treatment. METHODOLOGY/PRINCIPAL FINDINGS: In a post hoc analysis of a prospective cohort study, admission MBL concentrations were determined in 353 consecutive patients with an acute ischemic stroke of whom 287 and 66 patients received conservative and thrombolytic treatment, respectively. Stroke severity, infarction volume, and functional outcome were studied in relation to MBL concentrations at presentation to the emergency department. MBL levels on admission were not influenced by the time from symptom onset to presentation (p = 0.53). In the conservative treatment group patients with mild strokes at presentation, small infarction volumes or favorable outcomes after three months demonstrated 1.5 to 2.6-fold lower median MBL levels (p = 0.025, p = 0.0027 and p = 0.046, respectively) compared to patients with more severe strokes. Moreover, MBL deficient patients (>100 ng/ml) were subject to a considerably decreased risk of an unfavorable outcome three months after ischemic stroke (adjusted odds ratio 0.38, p>0.05) and showed smaller lesion volumes (mean size 0.6 vs. 18.4 ml, p = 0.0025). In contrast, no association of MBL concentration with infarction volume or functional outcome was found in the thrombolysis group. However, the small sample size limits the significance of this observation. CONCLUSIONS: MBL deficiency is associated with smaller cerebral infarcts and favorable outcome in patients receiving conservative treatment. Our data suggest an important role of the lectin pathway in the pathophysiology of cerebral I/R injury and might pave the way for new therapeutic interventions
Anisotropic Proton and Oxygen Ion Conductivity in Epitaxial Ba<sub>2</sub>In<sub>2</sub>O<sub>5</sub> Thin Films
Solid
oxide oxygen ion and proton conductors are a highly important
class of materials for renewable energy conversion devices like solid
oxide fuel cells. Ba<sub>2</sub>In<sub>2</sub>O<sub>5</sub> (BIO)
exhibits both oxygen ion and proton conduction, in a dry and humid
environment, respectively. In a dry environment, the brownmillerite
crystal structure of BIO exhibits an ordered oxygen ion sublattice,
which has been speculated to result in anisotropic oxygen ion conduction.
The hydrated structure of BIO, however, resembles a perovskite and
the protons in it were predicted to be ordered in layers. To complement
the significant theoretical and experimental efforts recently reported
on the potentially anisotropic conductive properties in BIO, we measure
here both the proton and oxygen ion conductivity along different crystallographic
directions. Using epitaxial thin films with different crystallographic
orientations, the charge transport for both charge carriers is shown
to be anisotropic. The anisotropy of the oxygen ion conduction can
indeed be explained by the layered structure of the oxygen sublattice
of BIO. The anisotropic proton conduction, however, further supports
the suggested ordering of the protonic defects in the material. The
differences in proton conduction along different crystallographic
directions attributed to proton ordering in BIO are of a similar extent
as those observed along different crystallographic directions in materials
where proton ordering is not present but where protons find preferential
conduction pathways through chainlike or layered structures
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