1,394 research outputs found
Design of a horizontal neutron reflectometer for the European Spallation Source
A design study of a horizontal neutron reflectometer adapted to the general
baseline of the long pulse European Spallation Source (ESS) is presented. The
instrument layout comprises solutions for the neutron guide, high-resolution
pulse shaping and beam bending onto a sample surface being so far unique in the
field of reflectometry. The length of this instrument is roughly 55 m, enabling
resolutions from 0.5% to 10%. The incident beam is
focussed in horizontal plane to boost measurements of sample sizes of 1*1
cm{^2} and smaller with potential beam deflection in both downward and upward
direction. The range of neutron wavelengths untilized by the instrument is 2 to
7.1 (12.2, ...) {\AA}, if every (second, ...) neutron source ulse is used.
Angles of incidence can be set between 0{\deg} and 9{\deg} with a total
accessible q-range from 4*10^{-3} {\AA}^{-1} up to 1 {\AA}^{-1}. The instrument
operates both in {\theta}/{\theta} (free liquid surfaces) and
{\theta}/2{\theta} (solid/liquid, air/solid interfaces) geometry. The
experimental setup will in particular enable direct studies on ultrathin films
(d ~ 10 {\AA}) and buried monolayers to multilayered structures of up to 3000
{\AA} total thickness. The horizontal reflectometer will further foster
investigations of hierarchical systems from nanometer to micrometer length
scale, as well as their kinetics and dynamical properties, in particular under
load (shear, pressure, external fields). Polarization and polarization analysis
as well as the GISANS option are designed as potential modules to be
implemented separately in the generic instrument layout. The instrument is
highly flexible and offers a variety of different measurement modes. With
respect to its mechanical components the instrument is exclusively based on
current technology. Risks of failure for the chosen setup are minimum.Comment: Matched to the version submitted to Nuclear Instruments and Methods
Scaling Behavior of Human Locomotor Activity Amplitude: Association with Bipolar Disorder
Scale invariance is a feature of complex biological systems, and abnormality of multi-scale behaviour may serve as an indicator of pathology. The hypothalamic suprachiasmatic nucleus (SCN) is a major node in central neural networks responsible for regulating multi-scale behaviour in measures of human locomotor activity. SCN also is implicated in the pathophysiology of bipolar disorder (BD) or manic-depressive illness, a severe, episodic disorder of mood, cognition and behaviour. Here, we investigated scaling behaviour in actigraphically recorded human motility data for potential indicators of BD, particularly its manic phase. A proposed index of scaling behaviour (Vulnerability Index [VI]) derived from such data distinguished between: [i] healthy subjects at high versus low risk of mood disorders; [ii] currently clinically stable BD patients versus matched controls; and [iii] among clinical states in BD patients
Domain wall pinning in a circular cross-section wire with modulated diameter
Domain wall propagation in cylindrical nanowires with modulations of diameter
is a key phenomenon to design physics-oriented devices, or a disruptive
three-dimensional magnetic memory. This chapter presents a combination of
analytical modelling and micromagnetic simulations, with the aim to present a
comprehensive panorama of the physics of pinning of domain walls at
modulations, when moved under the stimulus of a magnetic field or a
spin-polarized current. For the sake of considering simple physics, we consider
diameters of a few tens of nanometers at most, and accordingly domain walls of
transverse type. Modeling with suitable approximations provides simple scaling
laws, while simulations are more accurate, refining the results and defining
the range of validity of the models. While pinning increases with the relative
change of diameter, a key feature is the much larger efficiency of pinning at
an increase of diameter upon considering current rather than field, due to the
drastic decrease of current density related to the increase of diameter.Comment: 37 pages, 14 figures, overview chapte
Lixiviação de nitrogênio em um Cambissolo cultivado com pessegueiro e submetido à aplicação de composto orgânico.
A aplicação de composto orgânico em solos cultivados com pessegueiro pode potencializar a transferência de N por lixiviação. O trabalho objetivou avaliar a lixiviação de N em um solo cultivado com pessegueiro e submetido à aplicação de composto orgânico. Em um pomar comercial de pessegueiro no municÃpio de Bento Gonçalves (RS) foram instalados lisÃmetros a 20 cm de profundidade. O solo recebeu a aplicação de 0 e 144 litros de composto orgânico por planta-1 ano-1 nas safras de 2010, 2011 e 2012. A solução do solo foi coletada no perÃodo de julho a outubro de 2012 e submetida à análise de nitrato, amônio e N mineral. As maiores concentrações de N lixiviado foram encontradas no tratamento com 144 litros de composto orgânico por planta-1. A adubação com composto orgânico apresentou baixas concentrações de N lixiviado, o que pode contribuir com a redução de contaminação ambiental.Resumo expandido
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