2,662 research outputs found
Climate or rural development policy?
Being heavily energy dependent, it is not much of a surprise that Europe pays special attention to reducing the use of fossil fuels. Each one of the ten new member states is characterized by relatively low per capita energy consumption and relatively low energy efficiency, and the share of renewables in their energy mix tends to be low, too. The paper examines the problem when policy measures create a decrease in environmental capital instead of an increase. In this case it hardly seems justified to talk about environmental protection. The authors describe a case of a Hungarian rapeseed oil mill which would not be of too much interest on its own but given that almost all similar plants went bankrupt, there are some important lessons to learn from its survival. The enterprise the authors examined aimed at establishing a micro-regional network. They completed a brown-field development to establish a small plant on the premises of a former large agricultural cooperative. By partnering with the former employees and suppliers of the sometime cooperative, they enjoyed some benefits which all the other green-field businesses focusing on fuel production could not. The project improved food security, energy security and population retention as well
Quenched Narrow-Line Laser Cooling of 40Ca to Near the Photon Recoil Limit
We present a cooling method that should be generally applicable to atoms with
narrow optical transitions. This technique uses velocity-selective pulses to
drive atoms towards a zero-velocity dark state and then quenches the excited
state to increase the cooling rate. We demonstrate this technique of quenched
narrow-line cooling by reducing the 1-D temperature of a sample of neutral 40Ca
atoms. We velocity select and cool with the 1S0(4s2) to 3P1(4s4p) 657 nm
intercombination line and quench with the 3P1(4s4p) to 1S0(4s5s)
intercombination line at 553 nm, which increases the cooling rate eight-fold.
Limited only by available quenching laser power, we have transferred 18 % of
the atoms from our initial 2 mK velocity distribution and achieved temperatures
as low as 4 microK, corresponding to a vrms of 2.8 cm/s or 2 recoils at 657 nm.
This cooling technique, which is closely related to Raman cooling, can be
extended to three dimensions.Comment: 5 pages, 4 figures; Submitted to PRA Rapid Communication
Object Segmentation and Ground Truth in 3D Embryonic Imaging
Many questions in developmental biology depend on measuring the position and movement of individual cells within developing embryos. Yet, tools that provide this data are often challenged by high cell density and their accuracy is difficult to measure. Here, we present a three-step procedure to address this problem. Step one is a novel segmentation algorithm based on image derivatives that, in combination with selective post-processing, reliably and automatically segments cell nuclei from images of densely packed tissue. Step two is a quantitative validation using synthetic images to ascertain the efficiency of the algorithm with respect to signal-to-noise ratio and object density. Finally, we propose an original method to generate reliable and experimentally faithful ground truth datasets: Sparse-dense dual-labeled embryo chimeras are used to unambiguously measure segmentation errors within experimental data. Together, the three steps outlined here establish a robust, iterative procedure to fine-tune image analysis algorithms and microscopy settings associated with embryonic 3D image data sets
Absolute Frequency Measurements of the Hg^+ and Ca Optical Clock Transitions with a Femtosecond Laser
The frequency comb created by a femtosecond mode-locked laser and a
microstructured fiber is used to phase coherently measure the frequencies of
both the Hg^+ and Ca optical standards with respect to the SI second as
realized at NIST. We find the transition frequencies to be f_Hg=1 064 721 609
899 143(10) Hz and f_Ca=455 986 240 494 158(26) Hz, respectively. In addition
to the unprecedented precision demonstrated here, this work is the precursor to
all-optical atomic clocks based on the Hg^+ and Ca standards. Furthermore, when
combined with previous measurements, we find no time variations of these atomic
frequencies within the uncertainties of |(df_Ca/dt)/f_Ca| < 8 x 10^{-14}
yr^{-1}, and |(df_Hg/dt)/f_Hg|< 30 x 10^{-14} yr^{-1}.Comment: 6 pages, including 4 figures. RevTex 4. Submitted to Phys. Rev. Let
An atomic clock with instability
Atomic clocks have been transformational in science and technology, leading
to innovations such as global positioning, advanced communications, and tests
of fundamental constant variation. Next-generation optical atomic clocks can
extend the capability of these timekeepers, where researchers have long aspired
toward measurement precision at 1 part in . This milestone will
enable a second revolution of new timing applications such as relativistic
geodesy, enhanced Earth- and space-based navigation and telescopy, and new
tests on physics beyond the Standard Model. Here, we describe the development
and operation of two optical lattice clocks, both utilizing spin-polarized,
ultracold atomic ytterbium. A measurement comparing these systems demonstrates
an unprecedented atomic clock instability of after
only hours of averaging
The Wide Field Spectrograph (WiFeS)
This paper describes the Wide Field Spectrograph (WiFeS) under construction
at the Research School of Astronomy and Astrophysics (RSAA) of the Australian
National University (ANU) for the ANU 2.3m telescope at the Siding Spring
Observatory. WiFeS is a powerful integral field, double-beam, concentric,
image-slicing spectrograph designed to deliver excellent thoughput, wavelength
stability, spectrophotometric performance and superb image quality along with
wide spectral coverage throughout the 320-950 nm wavelength region. It provides
a 25x38 arcsec. field with 0.5 arcsec. sampling along each of twenty five 38X1
arcsec slitlets. The output format is optimized to match the 4096x4096 pixel
CCD detectors in each of two cameras individually optimized for the blue and
the red ends of the spectrum, respectively. A process of "interleaved
nod-and-shuffle" will be applied to permit quantum noise-limited sky
subtraction. Using VPH gratings, spectral resolutions of 3000 and 7000 are
provided. The full spectral range is covered in a single exposure at R=3000,
and in two exposures in the R=7000 mode. The use of transmissive coated optics,
VPH gratings and optimized mirror coatings ensures a throughput (including
telescope atmosphere and detector) > 30% over a wide spectral range. The
concentric image-slicer design ensures an excellent and uniform image quality
across the full field. To maximize scientific return, the whole instrument is
configured for remote observing, pipeline data reduction, and the accumulation
of calibration image libraries.Comment: Accepted for publication in Astrophysics & Space Science, 16 pages,
14 figure
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Fabrication and characterisation of Si micropillar PV structures
Arrays of vertical silicon micropillar radial junction solar cells have been fabricated by diffusion of direct application spin on dopant and from the vapour phase through proximity rapid thermal diffusion. The micropillars were fabricated by optical lithography and deep reactive ion etching. The micropillar arrays show superior antireflective properties over the measured spectrum and good correlation to finite difference time domain modelling of identical geometry arrays. Junctions formed by a conventional spin on doping process of phosphorus containing dopant solution produced Suns-Voc values in the region of 0·3 V. This value is likely due to difficulties encountered in achieving an even distribution of dopant over the entire surface of the arrays. An alternative method utilising spin on dopant but employing an intermediate vapour phase diffusion step produced promising results with Suns-Voc values reaching 0·5 V following a post-diffusion drive-in ste
Social and communicative functioning
It is widely acknowledged that the establishment of positive attachment relationships and communication with primary caregivers is an important outcome of social-emotional development in early childhood. Attachment security and communication abilities are also associated with key developmental achievements later in childhood, and indeed across the life-span. Research conducted with children with Down syndrome suggests that although differences in attention regulation and emotional responsivity may modify the developmental processes in some respects, the general patterns are similar to those in typically-developing children. It is known from research in this latter population that sensitivity and âmind-mindednessâ in caregiving are of key importance, as is the development of shared attentional focus. We argue that targeted research to identify the ways in which parents can most effectively support these core functions in the early development of children with Down syndrome should be a priority, as should involving parents as research partners in this endeavour
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