2,835 research outputs found
Optical Theorem and the Inversion of Cross Section Data for Atom Scattering from Defects on Surfaces
The information content and properties of the cross section for atom
scattering from a defect on a flat surface are investigated. Using the Sudden
approximation, a simple expression is obtained that relates the cross section
to the underlying atom/defect interaction potential. An approximate inversion
formula is given, that determines the shape function of the defect from the
scattering data. Another inversion formula approximately determines the
potential due to a weak corrugation in the case of substitutional disorder. An
Optical Theorem, derived in the framework of the Sudden approximation, plays a
central role in deriving the equations that conveniently relate the interaction
potential to the cross section. Also essential for the result is the
equivalence of the operational definition for the cross section for scattering
by a defect, given by Poelsema and Comsa, and the formal definition from
quantum scattering theory. This equivalence is established here. The inversion
result is applied to determine the shape function of an Ag atom on Pt(111) from
scattering data.Comment: 29 pages, 9 Postscript figures, more info available at
http://www.fh.huji.ac.il/~dan
Swiss ethnoveterinary knowledge on medicinal plants - a within-country comparison of Italian speaking regions with north-western German speaking regions
BACKGROUND:
Ethnoveterinary knowledge in Europe may play an important role as a basis for sustainable treatment options for livestock. Aims of our study were (a) to compare the ethnoveterinary practices of two culturally and sociodemographically different regions of Switzerland, (b) to compare results with earlier ethnoveterinary studies conducted in Switzerland and in adjacent Italian regions and, (c) to evaluate possible reasons for regional differences in European ethnoveterinary medicine.
METHODS:
25 interviews were conducted in 2014 in all Italian speaking regions (ItR) of Switzerland, and 31 interviews were held in five north-western German speaking Cantons (GeC). Semi-structured questionnaires were used to collect detailed information regarding plant species, mode of preparation, dosage, route of administration, category of use, origin of knowledge, frequency of use, and satisfaction with outcomes of the treatments.
RESULTS:
A total of 162 homemade remedies in ItR and 219 in GeC were reported, out of which 125 and 145, respectively, were reported to contain only one plant species (homemade single species herbal remedy report, HSHR). 44 ItR and 43 GeC plant species were reported to treat livestock, of which only a half were used in both regions. For each HSHR, we classified the treatment intention of all use reports (UR), leading to a total of 205 and 219 UR in ItR and GeC respectively. While cattle were the most often treated livestock species in both study regions, in ItR 40% of UR were administered to small ruminants. Main indications in both regions were gastrointestinal diseases and skin afflictions, but in ItR a high number of URs were reported as antiparasitics. URs were mainly handed down from the past generation, but in GeC the source of knowledge for 20% of URs were from courses. Regarding the used plant species, ItR showed a higher concordance with Swiss than Italian studies, but with some differences to all regions. A total of 22 (14 ItR; 8 GeC) plant species in this study have not been reported before in ethnoveterinary studies of Swiss and Italian alpine regions.
CONCLUSIONS:
ItR and GeC, show differences and similarities with respect to their own ethnoveterinary practices and earlier Swiss and Italian ethnoveterinary studies. Linguistic, geographical, as well as social and farm-structural conditions influence the regional ethnoveterinary knowledge. However, political borders seem to be more important than language or geographical barriers
He Scattering from Random Adsorbates, Disordered Compact Islands and Fractal Submonolayers: Intensity Manifestations of Surface Disorder
A theoretical study is made on He scattering from three fundamental classes
of disordered ad-layers: (a) Translationally random adsorbates, (b) disordered
compact islands and (c) fractal submonolayers. The implications of the results
to experimental studies of He scattering from disordered surfaces are
discussed, and a combined experimental-theoretical study is made for Ag
submonolayers on Pt(111). Some of the main theoretical findings are: (1)
Structural aspects of the calculated intensities from translationally random
clusters were found to be strongly correlated with those of individual
clusters. (2) Low intensity Bragg interference peaks appear even for scattering
from very small ad-islands, and contain information on the ad-island local
electron structure. (3) For fractal islands, just as for islands with a
different structure, the off-specular intensity depends on the parameters of
the He/Ag interaction, and does not follow a universal power law as previously
proposed in the literature. In the experimental-theoretical study of Ag on
Pt(111), we use first experimental He scattering data from low-coverage (single
adsorbate) systems to determine an empirical He/Ag-Pt potential of good
quality. Then, we carry out He scattering calculations for high coverage and
compare with experiments. The conclusions are that the actual experimental
phase corresponds to small compact Ag clusters of narrow size distribution,
translationally disordered on the surface.Comment: 36 double-spaced pages, 10 figures; accepted by J. Chem. Phys.,
scheduled to appear March 8. More info available at
http://www.fh.huji.ac.il/~dani
The role of working memory and contextual constraints in children's processing of relative clauses
An auditory sentence comprehension task investigated the extent to which the integration of contextual and structural cues was mediated by verbal memory span with 32 English-speaking 6- to 8-year old children. Spoken relative clause sentences were accompanied by visual context pictures which fully (depicting the actions described within the relative clause) or partially (depicting several referents) met the pragmatic assumptions of relativisation. Comprehension of the main and relative clauses of centre-embedded and right-branching structures was compared for each context. Pragmatically-appropriate contexts exerted a positive effect on relative clause comprehension, but children with higher memory spans demonstrated a further benefit for main clauses. Comprehension for centre-embedded main clauses was found to be very poor, independently of either context or memory span. The results suggest that children have access to adult-like linguistic processing mechanisms, and that sensitivity to extra-linguistic cues is evident in young children and develops as cognitive capacity increases
Cytopathology of Thyroid Nodules
Fine needle aspiradon biopsy is a simple and accurate means of obtaining a tissue diagnosis for a thyroid nodule. Our experience with 3,000 such biopsies and 242 surgically proven cancers has enabled us to characterize the cytologic presentations of the common nodular thyroid diseases. We can readily identify nodular goiter and papillary, poorly differentiated follicular, medullary, anaplastic, and metastatic cancers. Benign follicular neoplasms and well-differentiated follicular cancers cannot be separated with great accuracy, but useful predictions can be made. Care is required to recognize the cellular abnormalities of autoimmune thyroiditis and to diagnose the coexistence of this disease with malignant lymphoma
Inversion of Randomly Corrugated Surfaces Structure from Atom Scattering Data
The Sudden Approximation is applied to invert structural data on randomly
corrugated surfaces from inert atom scattering intensities. Several expressions
relating experimental observables to surface statistical features are derived.
The results suggest that atom (and in particular He) scattering can be used
profitably to study hitherto unexplored forms of complex surface disorder.Comment: 10 pages, no figures. Related papers available at
http://neon.cchem.berkeley.edu/~dan
Reconstruction of thermally-symmetrized quantum autocorrelation functions from imaginary-time data
In this paper, I propose a technique for recovering quantum dynamical
information from imaginary-time data via the resolution of a one-dimensional
Hamburger moment problem. It is shown that the quantum autocorrelation
functions are uniquely determined by and can be reconstructed from their
sequence of derivatives at origin. A general class of reconstruction algorithms
is then identified, according to Theorem 3. The technique is advocated as
especially effective for a certain class of quantum problems in continuum
space, for which only a few moments are necessary. For such problems, it is
argued that the derivatives at origin can be evaluated by Monte Carlo
simulations via estimators of finite variances in the limit of an infinite
number of path variables. Finally, a maximum entropy inversion algorithm for
the Hamburger moment problem is utilized to compute the quantum rate of
reaction for a one-dimensional symmetric Eckart barrier.Comment: 15 pages, no figures, to appear in Phys. Rev.
Treatment of organic livestock with medicinal plants : a systematic review of European ethnoveterinary research
Background: The EC Regulation for Organic Farming states that organic livestock should be treated preferably with phytotherapeutic products. In spite of the high importance of organic livestock in Europe, primarily ruminants, today almost no phytotherapeutic product is registered for livestock. Also, scientific information regarding veterinary phytotherapy is rare. The aim of this paper is to find approaches to cope with health problems of organic ruminants in Europe on the basis of findings from the European ethnoveterinary medicine (EuEVM). Methods: A systematic review of ethno-biomedicinal papers was conducted with the aid of the Scopus database, and 75 papers, from European countries were analyzed regarding ethnoveterinary information. Results: A total of 590 plant species referring to 102 different plant families are reported to be used for animal treatment, with Asteraceae, Fabaceae and Lamiaceae being the most important families. The traditional use of some plant species (e.g. mallow, chamomile, wormwood) corresponds with findings from recent scientific literature. The large number of less studied plant species, such as white lupin as an antiparasitic herb, and Helleborus spp. as potential immunostimulatory agent, opens an interesting field for future research. Conclusions: In general, EuEVM provides interesting treatment approaches for gastrointestinal and dermatological disorders as well as parasitosis. Findings regarding disorders of female genital or respiratory tract are less consistent.
Nevertheless, EuEVM offers a solid basis for stimulating research in veterinary phytotherapy in Europe with a perspective to solve animal health problems in organic or even nonorganic ruminant production
Airborne observations of aerosol microphysical properties and particle ageing processes in the troposphere above Europe
In-situ measurements of aerosol microphysical properties were performed in May 2008 during the EUCAARI-LONGREX campaign. Two aircraft, the FAAM BAe-146 and DLR Falcon 20, operated from Oberpfaffenhofen, Germany. A comprehensive data set was obtained comprising the wider region of Europe north of the Alps throughout the whole tropospheric column. Prevailing stable synoptic conditions enabled measurements of accumulating emissions inside the continental boundary layer reaching a maximum total number concentration of 19 000 particles cm<sup>−3</sup> stp. Ultra-fine particles as indicators for nucleation events were observed within the boundary layer during high pressure conditions and after updraft of emissions induced by frontal passages above 8 km altitude in the upper free troposphere. Aerosol ageing processes during air mass transport are analysed using trajectory analysis. The ratio of particles containing a non-volatile core (250 °C) to the total aerosol number concentration was observed to increase within the first 12 to 48 h from the particle source from 50 to 85% due to coagulation. Aged aerosol also features an increased fraction of accumulation mode particles of approximately 40% of the total number concentration. The presented analysis provides an extensive data set of tropospheric aerosol microphysical properties on a continental scale which can be used for atmospheric aerosol models and comparisons of satellite retrievals
Fractal Analysis of Protein Potential Energy Landscapes
The fractal properties of the total potential energy V as a function of time
t are studied for a number of systems, including realistic models of proteins
(PPT, BPTI and myoglobin). The fractal dimension of V(t), characterized by the
exponent \gamma, is almost independent of temperature and increases with time,
more slowly the larger the protein. Perhaps the most striking observation of
this study is the apparent universality of the fractal dimension, which depends
only weakly on the type of molecular system. We explain this behavior by
assuming that fractality is caused by a self-generated dynamical noise, a
consequence of intermode coupling due to anharmonicity. Global topological
features of the potential energy landscape are found to have little effect on
the observed fractal behavior.Comment: 17 pages, single spaced, including 12 figure
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