725 research outputs found
Spatial and temporal pulse shaping for lateral and depth resolved two-photon excited fluorescence contrast
We report combined temporal and spatial laser pulse shaping to perform lateral and depth dependent two-photon excited fluorescence of dyes. For generating the specific spatially and temporally phase tailored pulses a temporal pulse shaper and a subsequent spatial pulse shaper are employed. Simultaneous spatial and temporal shaping is presented for two-photon excited fluorescence by applying temporal third order phase functions on spatially different light field components. Moreover, the prospects of spatial shaping are demonstrated by applying various lateral two-photon fluorescence pattern. In particular, a depth dependent excitation of different dyes is performed which leads to a high axially resolved fluorescence contrast. The introduced spatial and temporal shaping technique provides new perspectives for biophotonic imaging applications
Types and correlates of school non-attendance in students with autism spectrum disorders
School non-attendance in autism spectrum disorders (ASD) has received very little attention to date. The study aimed to provide a comprehensive description of school non-attendance in students with ASD. Through an online survey, parents of 486 children (mean age 11 years) reported on school attendance over one month, and reasons for instances of non-attendance. On average, students missed five days of school of a possible 23 days. Persistent non-attendance (absent on 10%+ of available sessions) occurred among 43% of students. School non-attendance was associated with child older age, not living in a two-parent household, parental unemployment and, especially, attending a mainstream school. School refusal accounted for 43% of non-attendance. School exclusion and school withdrawal each accounted for 9% of absences. Truancy was almost non-existent. Non-problematic absenteeism (mostly related to medical appointments and illness) accounted for 32% of absences. Non-problematic absenteeism was more likely among those with intellectual disability, school refusal was more likely among older students, and school exclusion was more likely among students from single-parent, unemployed, and well educated households. Findings suggest school non-attendance in ASD is a significant issue, and that it is important to capture detail about attendance patterns and reasons for school non-attendance
Tunable steady-state domain wall oscillator with perpendicular magnetic anisotropy
We theoretically study domain wall oscillations upon the injection of a dc
current through a geometrically constrained wire with perpendicular magnetic
anisotropy. The oscillation frequency spectrum can be tuned by the injected
current density, but additionally by the application of an external magnetic
field independent of the power. The results of analytical calculations are
supported by micromagnetic simulations based on the Landau-Lifshitz-Gilbert
equation. The simple concept of our localized steady-state oscillator might
prove useful as a nanoscale microwave generator with possible applications in
telecommunication or for rf-assisted writing in magnetic hard drives.Comment: 10 pages, 3 figure
A traveling wave decelerator for neutral polar molecules
Recently, a decelerator for neutral polar molecules has been presented that
operates on the basis of macroscopic, three-dimensional, traveling
electrostatic traps (Osterwalder et al., Phys. Rev. A 81, 051401 (2010)). In
the present paper, a complete description of this decelerator is given, with
emphasis on the electronics and the mechanical design. Experimental results
showing the transverse velocity distributions of guided molecules are shown and
compared to trajectory simulations. An assessment of non-adiabatic losses is
made by comparing the deceleration signals from 13-CO with those from 12-CO and
with simulated signals.Comment: 10 pages, 7 figure
Energy relaxation and triplet formation
We combined femtosecond (fs) VIS pumpâIR probe spectroscopy with fs VIS
pumpâsupercontinuum probe spectroscopy to characterize the photoreaction of
the hexacoordinated Al(tpfc-Br8)(py)2 in a comprehensive way. Upon fs
excitation at âŒ400ânm in the Soret band, the excitation energy relaxes with a
time constant of (250â±â80) fs to the S2 and S1 electronic excited states.
This is evident from the rise time of the stimulated emission signal in the
visible spectral range. On the same time scale, narrowing of broad infrared
signals in the C=C stretching region around 1500âcmâ1 is observed. Energy
redistribution processes are visible in the vibrational and electronic
dynamics with time constants between âŒ2 ps and âŒ20 ps. Triplet formation is
detected with a time constant of (95â±â3) ps. This is tracked by the complete
loss of stimulated emission. Electronic transition of the emerging triplet
absorption band overlaps considerably with the singlet excited
stateabsorption. In contrast, two well separated vibrational marker bands for
triplet formation were identified at 1477âcmâ1 and at 1508âcmâ1. These marker
bands allow a precise identification of triplet dynamics in corrole systems
Current Concepts and Trends in Human-Automation Interaction
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugÀnglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The purpose of this panel was to provide a general overview and discussion of some of the most current and controversial concepts and trends in human-automation interaction. The panel was composed of eight researchers and practitioners. The panelists are well-known experts in the area and offered differing views on a variety of different human-automation topics. The range of concepts and trends discussed in this panel include: general taxonomies regarding stages and levels of automation and function allocation, individualized adaptive automation, automation-induced complacency, economic rationality and the use of automation, the potential utility of false alarms, the influence of different types of false alarms on trust and reliance, and a system-wide theory of trust in multiple automated aids
Combined temporal and spatial laser pulse shaping for two-photon excited fluorescence contrast improvement
We report on combined simultaneous temporal and spatial laser pulse shaping by utilizing light polarization properties. Thereto, a setup comprising a temporal pulse shaper, a waveplate, and a spatial shaper was developed and characterized by comparison with simulations. This enables to simultaneously shape one polarization component temporally and spatially while the perpendicular polarization component is modified temporally. The spatially and temporally modulated light fields were recorded and visualized by suitable contour plots, which was particularly demonstrated for cylindrically symmetric pulse profiles. Moreover, temporally and spatially shaped pulses were applied for two-photon excited fluorescence of dyes. These measurements were conducted by scanning third order phase functions for specific spatial pulse components which yields an enhanced contrast difference between fluorescing dyes. The presented temporal and spatial shaping method of ultrashort laser pulses has a high potential for biophotonic applications
Efficient chaining of seeds in ordered trees
We consider here the problem of chaining seeds in ordered trees. Seeds are
mappings between two trees Q and T and a chain is a subset of non overlapping
seeds that is consistent with respect to postfix order and ancestrality. This
problem is a natural extension of a similar problem for sequences, and has
applications in computational biology, such as mining a database of RNA
secondary structures. For the chaining problem with a set of m constant size
seeds, we describe an algorithm with complexity O(m2 log(m)) in time and O(m2)
in space
Domain-wall depinning assisted by pure spin currents
We study the depinning of domain walls by pure diffusive spin currents in a
nonlocal spin valve structure based on two ferromagnetic permalloy elements
with copper as the nonmagnetic spin conduit. The injected spin current is
absorbed by the second permalloy structure with a domain wall and from the
dependence of the wall depinning field on the spin current density we find an
efficiency of 6*10^{-14}T/(A/m^2), which is more than an order of magnitude
larger than for conventional current induced domain wall motion. Theoretically
we reproduce this high efficiency, which arises from the surface torques
exerted by the absorbed spin current that lead to efficient depinning.Comment: 11 pages, 3 figures, accepted for publication in Phys. Rev. Let
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