7,976 research outputs found
Organic Agriculture in Albania - Sector Study 2011
FiBL, working with local partners, has compiled the facts and figures in a study presenting the organic sector's drivers and determinants. The study is a valuable resource for local stakeholders and interested trading companies
Atomic matter wave scanner
We report on the experimental realization of an atom optical device, that
allows scanning of an atomic beam. We used a time-modulated evanescent wave
field above a glass surface to diffract a continuous beam of metastable Neon
atoms at grazing incidence. The diffraction angles and efficiencies were
controlled by the frequency and form of modulation, respectively. With an
optimized shape, obtained from a numerical simulation, we were able to transfer
more than 50% of the atoms into the first order beam, which we were able to
move over a range of 8 mrad.Comment: 4 pages, 4 figure
MgII absorption systems with W_0 > 0.1 \AA for a radio selected sample of 77 QSOs and their associated magnetic fields at high redshifts
We present a catalogue of MgII absorption systems obtained from high
resolution UVES/VLT data of 77 QSOs in the redshift range 0.6 < z < 2.0, and
down to an equivalent width W_0 > 0.1 \AA. The statistical properties of our
sample are found to be in agreement with those from previous work in the
literature. However, we point out that the previously observed increase with
redshift of dN/dz for weak absorbers, pertains exclusively to very weak
absorbers with W_0 < 0.1 \AA. Instead, dN/dz for absorbers with W_0 in the
range 0.1-0.3 \AA actually decreases with redshift, similarly to the case of
strong absorbers. We then use this catalogue to extend our earlier analysis of
the links between the Faraday Rotation Measure of the quasars and the presence
of intervening MgII absorbing systems in their spectra. In contrast to the case
with strong MgII absorption systems W_0 > 0.3 \AA, the weaker systems do not
contribute significantly to the observed Rotation Measure of the background
quasars. This is possibly due to the higher impact parameters of the weak
systems compared to strong ones, suggesting that the high column density
magnetized material that is responsible for the Faraday Rotation is located
within about 50 kpc of the galaxies. Finally, we show that this result also
rules out the possibility that some unexpected secondary correlation between
the quasar redshift and its intrinsic Rotation Measure is responsible for the
association of high Rotation Measure and strong intervening MgII absorption
that we have presented elsewhere, since this would have produced an equal
effect for the weak absorption line systems, which exhibit a very similar
distribution of quasar redshifts.Comment: Accepted for publication in ApJ. 12 pages, 8 figure
Klinische Evaluation eines Überdruckventils für Kindertuben mit Cuff
Zusammenfassung: Ziel: Zum sicheren Einsatz von Tuben mit Cuff bei Kindern ist eine Cuffdruckbegrenzung bei 20-25cmH2O von entscheidender Bedeutung. Ziel der Studie war es, die Zuverlässigkeit und den Nutzen eines neuen Cuffüberdruckventils (Öffnungsdruck 20cmH2O) in Kombination mit Tuben mit Cuff in der klinischen Anwendung bei Kindern zu evaluieren. Methodik: In einer prospektiven Studie wurde der Cuffdruck bei Kindern und Adoleszenten, die mithilfe von Tuben mit Cuff intubiert waren und eine Sevofluran-Lachgas-Anästhesie erhielten, protokolliert. Das Cuffdruckentlastungsventil wurde zwischen Cuffmanometer und Pilotballon geschaltet. Bei 25Patienten wurde die Messung vom initialen Öffnungsdruck (GruppeA) aus und bei weiteren 25Patienten vom minimalen Dichtungsdruck (GruppeB) aus gestartet. Ergebnisse: Fünfzig Patienten im Alter von 0,4 bis 17,8Jahren (Median 7,4Jahre) wurden in die Studie aufgenommen. Der Öffnungsdruck (GruppeA) lag bei 19,7±0,8cmH2O und der minimale Dichtungscuffdruck (GruppeB) bei 11,7±2,9cmH2O (Variationsbreite 6-16cmH2O). Die mittleren Cuffdruckwerte in GruppeA stabilisierten sich bei 20,4±1,6cmH2O, während sich die Cuffdruckwerte in GruppeB bei 16,5±3,3cmH2O einpendelten. Bei einem Patienten der GruppeA kam es zu einem Überschreiten der Cuffdruckgrenze von 25cmH2O; dies hatte eine manuelle Entlastung gemäß Protokoll zur Folge. Insgesamt waren während 103,1Messstunden 24Nachfüllmanöver (14 in GruppeA und 10 in GruppeB) wegen Druckabfalls mit hörbarer Luftleckage notwendig. Die meisten davon waren durch Druckerhöhungen bei der Umlagerung des Patienten bzw. nachfolgender Entlastung durch das Überdruckventil verursacht. Schlussfolgerung: Die vorliegende Untersuchung zeigt, dass das eingesetzte, einfache und leicht zu handhabende Cuffüberdruckventil zur intraoperativen Cuffdrucklimitierung bei Kindern und Adoleszenten mit geblockten Trachealtuben geeignet is
Implementation of mean-timing and subsequent logic functions on an FPGA
This article describes the implementation of a mean-timer and coincidence
logic on a Virtex-5 FPGA for trigger purposes in a particle physics experiment.
The novel feature is that the mean-timing and the coincidence logic are not
synchronized with a clock which allows for a higher resolution of approximately
400 ps, not limited by a clock frequency.Comment: 15 pages, 11 figure
Sum Rules and Moments of the Nucleon Spin Structure Functions
The nucleon has been used as a laboratory to investigate its own spin
structure and Quantum Chromodynamics. New experimental data on nucleon spin
structure at low to intermediate momentum transfers combined with existing high
momentum transfer data offer a comprehensive picture of the transition region
from the {\it confinement} regime of the theory to its {\it asymptotic freedom}
regime. Insight for some aspects of the theory is gained by exploring lower
moments of spin structure functions and their corresponding sum rules (i.e. the
Gerasimov-Drell-Hearn, Bjorken and Burkhardt-Cottingham). These moments are
expressed in terms of an operator product expansion using quark and gluon
degrees of freedom at moderately large momentum transfers. The sum rules are
verified to a good accuracy assuming that no singular behavior of the structure
functions is present at very high excitation energies. The higher twist
contributions have been examined through the moments evolution as the moments
evolution as the momentum transfer varies from higher to lower values.
Furthermore, QCD-inspired low-energy effective theories, which explicitly
include chiral symmetry breaking, are tested at low momentum transfers. The
validity of these theories is further examined as the momentum transfer
increases to moderate values. It is found that chiral perturbation calculations
agree reasonably well with the first moment of the spin structure function
at momentum transfer of 0.1 GeV but fail to reproduce the neutron
data in the case of the generalized polarizability .Comment: 21 pages, 4 figures, review for Modern Physics Letters A. Minor
modifications in text and improved quality for one figure. Corrected mistakes
in section
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