1,510 research outputs found
The Effects of MIMO Antenna System Parameters and Carrier Frequency on Active Control Suppression of EM Fields
In this paper we propose a new approach employing adaptive active control algorithms combined with a Multiple-Input Multiple-Output (MIMO) antenna system to suppress the electromagnetic field at a certain volume in space (e.g., at the human head). We will investigate the effects of the size and number of MIMO antenna elements on the system performance and test the algorithms at different carrier frequencies (e.g., GSM bands and UMTS)
Search for decay of Eu to the first excited level of Pm using underground -ray spectrometry
The alpha decay of Eu to the first excited level of Pm
(, keV) was searched for at the HADES underground
laboratory ( m w.e.). A sample of high purity europium oxide with
mass of 303 g and a natural isotopic composition has been measured over 2232.8
h with a high energy resolution ultra-low background n-type semi-planar HPGe
detector (40 cm) with sub-micron deadlayer. The new improved half-life
limit has been set as yr at 68% C.L.
Possibilities to improve the sensitivity of the experiment, which is already
near the theoretical predictions, are discussed. New half-life limit for
decay of Eu is also set as
yr.Comment: 11 pages, 5 figures, 2 tables, 18 reference
Pulse shape discrimination performance of Inverted Coaxial Ge detectors
We report on the characterization of two inverted coaxial Ge detectors in the
context of being employed in future Ge neutrinoless double beta
() decay experiments. It is an advantage that such detectors
can be produced with bigger Ge mass as compared to the planar Broad Energy Ge
detectors (BEGe) that are currently used in the GERDA decay
experiment. This will result in lower background for the search of
decay due to a reduction of cables, electronics and holders.
The measured resolution near the Ge Q-value at 2039 keV is 2.5 keV and
their pulse-shape characteristics are similar to BEGe-detectors. It is
concluded that this type of Ge-detector is suitable for usage in Ge
decay experiments
Nonlinear optical properties of a channel waveguide produced with crosslinkable ferroelectric liquid crystals
A binary mixture of ferroelectric liquid crystals (FLCs) was used for the
design of a channel waveguide. The FLCs possess two important functionalities:
a chromophore with a high hyperpolarizability and photoreactive groups.
The smectic liquid crystal is aligned in layers parallel to the glass plates in
a sandwich geometry. This alignment offers several advantages, such as that
moderate electric fields are sufficient to achieve a high degree of polar
order. The arrangement was then permanently fixed by photopolymerization which
yielded a polar network possessing a high thermal and mechanical stability
which did not show any sign of degradation within the monitored period of
several months. The linear and nonlinear optical properties have been measured
and all four independent components of the nonlinear susceptibility tensor
have been determined. The off-resonant -coefficients are remarkably
high and comparable to those of the best known inorganic materials. The
alignment led to an inherent channel waveguide for p-polarized light without
additional preparation steps. The photopolymerization did not induce scattering
sites in the waveguide and the normalized losses were less than 2 dB/cm. The
material offers a great potential for the design of nonlinear optical devices
such as frequency doublers of low power laser diodes.Comment: LaTeX2e article, 15 pages, 10 figures, 11 EPS files, submitted to
Physical Review
On the Underground Production of High Purity Germanium Detectors
Detectors based on high purity germanium (HPGe) are used in numerous deep underground experiments world-wide aiming at detecting rare events like double beta decay and interactions of dark matter. These detectors require the lowest possible background. A significant part of the background is due to radionuclides produced by cosmic-ray interactions with the germanium crystal. This report gives quantitative data on this activation and discusses the possible solutions. The first solution is to optimise the logistics during the crystal and detector fabrication so that the germanium spends a minimum time above ground. The second solution is to implement one or several (up to 12) production steps underground. The report also makes estimates on the future needs for germanium produced underground and the costs involved.JRC.D.4-Isotope measurement
Nursing assistants matters—An ethnographic study of knowledge sharing in interprofessional practice
© 2017 John Wiley & Sons Ltd Interprofessional collaboration involves some kind of knowledge sharing, which is essential and will be important in the future in regard to the opportunities and challenges in practices for delivering safe and effective health care. Nursing assistants are seldom mentioned as a group of health care workers that contribute to interprofessional collaboration in health care practice. The aim of this ethnographic study was to explore how the nursing assistants’ knowledge can be shared in a team on a spinal cord injury rehabilitation ward. Using a sociomaterial perspective on practice, we captured different aspects of interprofessional collaboration in health care. The findings reveal how knowledge was shared between professionals, depending on different kinds of practice architecture. These specific cultural–discursive, material–economic, and social–political arrangements enabled possibilities through which nursing assistants’ knowledge informed other practices, and others’ knowledge informed the practice of nursing assistants. By studying what health care professionals actually do and say in practice, we found that the nursing assistants could make a valuable contribution of knowledge to the team
A and B antigen levels acquired by group O donor-derived erythrocytes following ABO-non-identical transfusion or minor ABO-incompatible haematopoietic stem cell transplantation
BACKGROUND AND OBJECTIVES: ABO-incompatible haematopoietic stem cell transplantation (HSCT) presents a challenge to blood component transfusion. The aim of this study was to investigate the weak blood group A or B antigen expression by donor-derived group O red blood cells (RBC) observed following transfusion or minor ABO-incompatible HSCT. In addition, in vitro experiments were performed to elucidate possible mechanisms underlying this phenomenon.MATERIALS AND METHODS: A sensitive flow cytometry assay for the semi-quantification of RBC A/B antigen levels was used to assess patient samples and evaluate in vitro experiments.RESULTS: Analysis of blood samples from patients, originally typed as A, B and AB but recently transplanted or transfused with cells from group O donors, revealed the A antigen expression on donor-derived RBC, ranging from very low levels in non-secretor individuals to almost subgroup Ax -like profiles in group A secretors. The B antigen expression was less readily detectable. In vitro experiments, in which group O donor RBC were incubated with (i) group A/B secretor/non-secretor donor plasma or (ii) group A/B donor RBC in the absence of plasma, supported the proposed adsorption of A/B antigen-bearing glycolipids from secretor plasma but also indicated a secretor-independent mechanism for A/B antigen acquisition as well as direct cell-to-cell transfer of ABO antigens.CONCLUSION: The in vivo conversion of donor-derived blood group O RBC to ABO subgroup-like RBC after transfusion or minor ABO-incompatible HSCT raises the question of appropriate component selection. Based on these data, AB plasma should be transfused following ABO-incompatible HSCT
Low-Background gamma counting at the Kimballton Underground Research Facility
The next generation of low-background physics experiments will require the
use of materials with unprecedented radio-purity. A gamma-counting facility at
the Kimballton Underground Research Facility (KURF) has been commissioned to
perform initial screening of materials for radioactivity primarily from
nuclides in the 238U and 232Th decay chains, 40K and cosmic-ray induced
isotopes. The facility consists of two commercial low-background high purity
germanium (HPGe) detectors. A continuum background reduction better than a
factor of 10 was achieved by going underground. This paper describes the
facility, detector systems, analysis techniques and selected assay results.Comment: 7 pages, 7 figures. Submitted to NIM
Highly sensitive gamma-spectrometers of GERDA for material screening: Part I
The GERDA experiment aims to search for the neutrinoless double beta-decay of
76Ge and possibly for other rare processes. The sensitivity of the first phase
is envisioned to be more than one order of magnitude better than in previous
neutrinoless double beta-decay experiments. This implies that materials with
ultra-low radioactive contamination need to be used for the construction of the
detector and its shielding. Therefore the requirements on material screening
include high-sensitivity low-background detection techniques and long
measurement times. In this article, an overview of material-screening
laboratories available to the GERDA collaboration is given, with emphasis on
the gamma-spectrometry. Additionally, results of an intercomparison of the
evaluation accuracy in these laboratories are presented.Comment: Featured in: Proceedings of the XIV International Baksan School
"Particles and Cosmology" Baksan Valley, Kabardino-Balkaria, Russia, April
16-21,2007. INR RAS, Moscow 2008. ISBN 978-5-94274-055-9, pp. 228-232; (5
pages, 0 figures
Entropy gives rise to topologically associating domains
We investigate chromosome organization within the nucleus using polymer models whose formulation is closely guided by experiments in live yeast cells. We employ bead-spring chromosome models together with loop formation within the chains and the presence of nuclear bodies to quantify the extent to which these mechanisms shape the topological landscape in the interphase nucleus. By investigating the genome as a dynamical system, we show that domains of high chromosomal interactions can arise solely from the polymeric nature of the chromosome arms due to entropic interactions and nuclear confinement. In this view, the role of bio-chemical related processes is to modulate and extend the duration of the interacting domains
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