341 research outputs found
Diet diversification through local foods: experiences from traditional vegetable promotion work in Kenya
Estimation of genetic parameters and detection of chromosomal regions affecting the major milk proteins and their post translational modifications in Danish Holstein and Danish Jersey cattle
Linkage disequilibrium plot (r 2) of the DGAT region in the Danish Jersey breed. (PNG 342 kb
Design of Strongly Modulating Pulses to Implement Precise Effective Hamiltonians for Quantum Information Processing
We describe a method for improving coherent control through the use of
detailed knowledge of the system's Hamiltonian. Precise unitary transformations
were obtained by strongly modulating the system's dynamics to average out
unwanted evolution. With the aid of numerical search methods, pulsed
irradiation schemes are obtained that perform accurate, arbitrary, selective
gates on multi-qubit systems. Compared to low power selective pulses, which
cannot average out all unwanted evolution, these pulses are substantially
shorter in time, thereby reducing the effects of relaxation. Liquid-state NMR
techniques on homonuclear spin systems are used to demonstrate the accuracy of
these gates both in simulation and experiment. Simulations of the coherent
evolution of a 3-qubit system show that the control sequences faithfully
implement the unitary operations, typically yielding gate fidelities on the
order of 0.999 and, for some sequences, up to 0.9997. The experimentally
determined density matrices resulting from the application of different control
sequences on a 3-spin system have overlaps of up to 0.99 with the expected
states, confirming the quality of the experimental implementation.Comment: RevTeX3, 11 pages including 2 tables and 5 figures; Journal of
Chemical Physics, in pres
Experimental ionization of atomic hydrogen with few-cycle pulses
We present the first experimental data on strong-field ionization of atomic
hydrogen by few-cycle laser pulses. We obtain quantitative agreement at the 10%
level between the data and an {\it ab initio} simulation over a wide range of
laser intensities and electron energies
Diffuse versus square-well confining potentials in modelling @C atoms
Attention: this version- of the manuscript differs from its previously
uploaded version- (arXiv:1112.6158v1) and subsequently published in 2012 J.
Phys. B \textbf{45} 105102 only by a removed typo in Eq.(2) of version-;
there was the erroneous factor "2" in both terms in the right-hand-side of the
Eq.(2) of version-. Now that the typo is removed, Eq.(2) is correct.
A perceived advantage for the replacement of a discontinuous square-well
pseudo-potential, which is often used by various researchers as an
approximation to the actual C cage potential in calculations of
endohedral atoms @C, by a more realistic diffuse potential is
explored. The photoionization of endohedral H@C and Xe@C is
chosen as the case study. The diffuse potential is modelled by a combination of
two Woods-Saxon potentials. It is demonstrated that photoionization spectra of
@C atoms are largely insensitive to the degree of diffuseness
of the potential borders, in a reasonably broad range of 's.
Alternatively, these spectra are found to be insensitive to discontinuity of
the square-well potential either. Both potentials result in practically
identical calculated spectra. New numerical values for the set of square-well
parameters, which lead to a better agreement between experimental and
theoretical data for @C spectra, are recommended for future studies.Comment: 11 pages, 4 figure
Adaptation des sorghos du Mali à la variabilité climatique
Il est couramment admis que la sécheresse en Afrique de l'Ouest a entraîné l'adoption par les paysans de variétés de sorgho plus précoces que les cultivars traditionnels. Pour mesurer l'évolution récente du cycle des sorghos du Mali, nous avons étudié la phénologie de deux collections de variétés locales prospectées à 20 ans d'intervalle en 1978 et en 2000. Les dates de début et de fin de saison des pluies ont été calculées pour tous les villages échantillonnés. La sensibilité des cultivars à la photopériode a été mesurée à l'aide d'un essai comportant deux dates de semis. Un modèle permet d'étudier l'adaptation des variétés au climat en tenant compte de la latitude et du régime des pluies de leurs zones d'origines. Le déficit pluviométrique n'a pas entraîné un raccourcissement important des cycles végétatifs. En 20 ans, le cycle moyen des cultivars locaux s'est raccourci de 5 jours. Pour des latitudes inférieures à 14° N, la grande majorité des cultivars sont photopériodiques, la floraison des variétés se produit dans les 20 jours qui précèdent la date moyenne de fin de la saison des pluies. Ce caractère permet d'optimiser l'alimentation en eau des cultures et d'éviter de nombreuses contraintes biotiques. Pour des latitudes supérieures ou égales à 14° N, la floraison moyenne coïncide avec la fin de saison. On note la présence simultanée de variétés tardives et précoces. Dans ces régions, la culture du sorgho dépend moins de la pluviométrie car les systèmes traditionnels valorisent des situations diversifiées et les reports d'eau sur les toposéquences. Cette diversité des cycles contribue à sécuriser la production agricole en zone aride. Ce travail permet de guider les programmes de sélection dans la définition d'idéotypes spécifiquement adaptés à la gamme d'environnements climatiques rencontrés dans la région. (Résumé d'auteur
A decision maxim for efficient task realization within analytical network infrastructures
Faced with the increasing needs of companies, optimal dimensioning of IT hardware is becoming challenging for decision makers. In terms of analytical infrastructures, a highly evolutionary environment causes volatile, time-dependent workloads in its components, and intelligent, flexible task distribution between local systems and cloud services is attractive. With the aim of developing a flexible and efficient design for analytical infrastructures, this paper proposes a flexible architecture model, which allocates tasks following a machine-specific decision heuristic. A simulation benchmarks this system with existing strategies and identifies the new decision maxim as superior in a first scenario-based simulation.Partly funded by the Advanced Sensor Networks SARChI Chair program, co-hosted by the University of Pretoria (UP) and Council for Scientific and Industrial Research (CSIR), through the National Research Foundation (NRF) of South Africa.https://www.elsevier.com/locate/dss2019-08-01hj2018Electrical, Electronic and Computer Engineerin
Personality Traits in Miners with Past Occupational Elemental Mercury Exposure
In this study, we evaluated the impact of long-term occupational exposure to elemental mercury vapor (Hg(0)) on the personality traits of ex-mercury miners. Study groups included 53 ex-miners previously exposed to Hg(0) and 53 age-matched controls. Miners and controls completed the self-reporting Eysenck Personality Questionnaire and the Emotional States Questionnaire. The relationship between the indices of past occupational exposure and the observed personality traits was evaluated using Pearson’s correlation coefficient and on a subgroup level by machine learning methods (regression trees). The ex-mercury miners were intermittently exposed to Hg(0) for a period of 7–31 years. The means of exposure-cycle urine mercury (U-Hg) concentrations ranged from 20 to 120 μg/L. The results obtained indicate that ex-miners tend to be more introverted and sincere, more depressive, more rigid in expressing their emotions and are likely to have more negative self-concepts than controls, but no correlations were found with the indices of past occupational exposure. Despite certain limitations, results obtained by the regression tree suggest that higher alcohol consumption per se and long-term intermittent, moderate exposure to Hg(0) (exposure cycle mean U-Hg concentrations > 38.7 < 53.5 μg/L) in interaction with alcohol remain a plausible explanation for the depression associated with negative self-concept found in subgroups of ex-mercury miners. This could be one of the reason for the higher risk of suicide among miners of the Idrija Mercury Mine in the last 45 years
Neuronal Sprouting and Reorganization in Bone Tissue Infiltrated by Human Breast Cancer Cells
BACKGROUND: Pain is a common complication for patients with metastatic bone disease. Animal models suggest that the pain, in part, is driven by pathological sprouting and reorganization of the nerve fibers innervating the bone. Here, we investigate how these findings translate to humans.METHODS: Bone biopsies were collected from healthy volunteers (n = 7) and patients with breast cancer and metastatic bone disease (permissions H-15000679, S-20180057 and S-20110112). Cancer-infiltrated biopsies were from patients without recent anticancer treatment (n = 10), patients with recent anticancer treatment (n = 10), and patients with joint replacement surgery (n = 9). Adjacent bone sections were stained for (1) protein gene product 9.5 and CD34, and (2) cytokeratin 7 and 19. Histomorphometry was used to estimate the area of bone marrow and tumor burden. Nerve profiles were counted, and the nerve profile density calculated. The location of each nerve profile within 25 μm of a vascular structure and/or cancer cells was determined.RESULTS: Cancer-infiltrated bone tissue demonstrated a significantly higher nerve profile density compared to healthy bone tissue. The percentage of nerve profiles found close to vascular structures was significantly lower in cancer-infiltrated bone tissue. No difference was found in the percentage of nerve profiles located close to cancer between the subgroups of cancer-infiltrated bone tissue. Interestingly, no correlation was found between nerve profile density and tumor burden.CONCLUSIONS: Together, the increased nerve profile density and the decreased association of nerve profiles to vasculature strongly suggests that neuronal sprouting and reorganization occurs in human cancer-infiltrated bone tissue.</p
Attosecond delays in photoionization studied with coherent-controlled FEL
When an electron is ejected from an atom after absorption of a photon, the photoelectron wave packet has an extremely short group delay between the photon absorption and the electron emission. This interval, called the Eisenbud-Wigner-Smith delay, is on the order of a few attoseconds. Here, we present a new method to measure the photoemission delay, using coherent-controlled free-electron laser pulses
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