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Processing of Silicon Carbide by Laser Micro Sintering
Silicon carbide – a solid with covalent bonds - is conventionally synthesized via the Acheson
process. Usually solid bodies of silicon carbide with definite shapes are generated from the
grained material via hot isostatic pressing or liquid phase sintering. Both processes are
conducted under well-controlled temperature regimes. Applying the freeform fabrication
technique “Laser Micro Sintering” poses a big challenge to experimental skill due to the nonequilibrium conditions that are characteristic features of laser material processing.
Successive layers SiC layers with a thickness of 1ÎĽm were processed with coherent
radiation of 1064 nm. The specific behavior of two different silicon carbide powders - one of
them blended with additives - are reported along with interpretational approaches.Mechanical Engineerin
POD for optimal control of the Cahn-Hilliard system using spatially adapted snapshots
The present work considers the optimal control of a convective Cahn-Hilliard
system, where the control enters through the velocity in the transport term. We
prove the existence of a solution to the considered optimal control problem.
For an efficient numerical solution, the expensive high-dimensional PDE systems
are replaced by reduced-order models utilizing proper orthogonal decomposition
(POD-ROM). The POD modes are computed from snapshots which are solutions of the
governing equations which are discretized utilizing adaptive finite elements.
The numerical tests show that the use of POD-ROM combined with spatially
adapted snapshots leads to large speedup factors compared with a high-fidelity
finite element optimization
Our first clinical experience with radiosynoviorthesis by means of 166Ho-holmium-boro-macroaggregates
BACKGROUND: In this paper, we evaluate the therapeutic and
adverse effects of the application of 166-holmium-boro-macroaggregates
(HMBA) in radiosynovectomy (RSO) of the knees.
We assessed the efficacy and safety of 166Ho-HBMA in a prospective
clinical trial in patients suffering from chronic synovitis.
MATERIAL AND METHODS: An effective component of radiopharmaceutical
166Ho-boro-macroaggregates is radionuclide
166Ho which has both β-emission and γ-emission. The physical
half-life time of 166Ho is 26.8 hours. After application of the radiopharmaceutical
into a joint cavity, the effect of β-emission
causes radiation necrosis of pathologically changed (inflamed)
synovial membrane. From 15th April 2005, we have started RSO
of knees by means of new radiopharmaceutical 166Ho-boro-macroaggregates
in patients with gonarthrosis, rheumatoid arthritis,
chronic synovitis, psoriatic arthritis, gout arthropathy. Seventeen
intra-articular injections were performed in fifteen patients
receiving a mean activity of 972 MBq (range: 904-1057 MBq)
166Ho-HMBA. The patients were hospitalized for three days. Side
effects were evaluated during hospital stay and after 6-8 weeks.
Static scintigraphy of knee joints and measurements of blood
radioactivity were performed. Therapeutic effects were evaluated
after 6-8 weeks.
RESULTS: In 2 hours and 2 days after application, we proved,
by means of knee and inguinal scintigraphy, only insignificant
radiopharmaceutical leakage from the joint cavity to the inguinal
lymph nodes in four patients. In treated patients, no serious
adverse effects occurred. Nine patients were without complaints;
4 patients had slight knee exsudation and 2 patients had great
exsudation. Therapeutic effects after 6-8 weeks were as follows:
2 patients were without pain, 9 with lower pain, 3 with the
same pain and 1 patient with increased pain. Joint motion was
improved in 7 patients, remained the same in 7 patients and
was impaired in 1 patient. Analgesics consumption was lower
in 5 patients, the same in 9 patients and greater in 1 patient.
Knee exsudation was absent in 2 patients, lower in 4 patients,
the same in 6 patients and greater in 3 patients.
CONCLUSIONS: We proved only insignificant radiopharmaceutical
leakage from the joint cavity to the inguinal lymph nodes.
Six patients had early slight or great radiation synovitis. The
possible cause could be rather high applicated activity. One
can take into consideration its reduction. Therapeutic effects
can be precisely evaluated after a longer time interval than was
possible for us (6-8 weeks after RSO). 166Ho-boro-macroaggregates
can extend the scale of clinically used radiopharmaceuticals
for RSO.
This paper is presented in the scope of the first stage of clinical
evaluation of synovectomy application of holmium-boro-macroaggregates
The impact of corporate philanthropy on reputation for corporate social performance
This study seeks to examine the mechanisms by which a corporation’s use of philanthropy affects its reputation for corporate social performance (CSP), which the authors conceive of as consisting of two dimensions: CSP awareness and CSP perception. Using signal detection theory (SDT), the authors model signal amplitude (the amount contributed), dispersion (number of areas supported), and consistency (presence of a corporate foundation) on CSP awareness and perception. Overall, this study finds that characteristics of firms' portfolio of philanthropic activities are a greater predictor of CSP awareness than of CSP perception. Awareness increases with signal amplitude, dispersion, and consistency. CSP perception is driven by awareness and corporate reputation. The authors’ contention that corporate philanthropy is a complex variable is upheld, as we find that CSP signal characteristics influence CSP awareness and perception independently and asymmetrically. The authors conclude by proposing avenues for future research
Enhanced characterization of the zebrafish brain as revealed by super-resolution track-density imaging
In this study, we explored the use of super-resolution track-density imaging (TDI) for neuroanatomical characterization of the adult zebrafish brain. We compared the quality of image contrast and resolution obtained with T-2* magnetic resonance imaging (MRI), diffusion tensor-based imaging (DTI), TDI, and histology. The anatomical structures visualized in 5 mu m TDI maps corresponded with histology. Moreover, the super-resolution property and the local-directional information provided by directionally encoded color TDI facilitated delineation of a larger number of brain regions, commissures and small white matter tracks when compared to conventional MRI and DTI. In total, we were able to visualize 17 structures that were previously unidentifiable using MR microimaging, such as the four layers of the optic tectum. This study demonstrates the use of TDI for characterization of the adult zebrafish brain as a pivotal tool for future phenotypic examination of transgenic models of neurological diseases
Genome size and organization in the blacklegged tick, \u3ci\u3eIxodes scapularis\u3c/i\u3e and the Southern cattle tick, \u3ci\u3eBoophilus microplus\u3c/i\u3e
Genome sizes and the organization of repetitive DNA were determined in the hard ticks Ixodes scapularis and Boophilus microplus using reassociation kinetics. The I. scapularis genome contains ~ 2.15 pg (2.1 × 10 3 Mbp) of DNA and consists of no foldback (FB), 27% highly repetitive (HR), 39% moderately repetitive (MR), and 34% unique DNA. The B. microplus genome contains 7.5 pg (7.1 × 10 3 Mbp) DNA, and consists of 0.82% FB, 31% HR, 38% MR, and 30% unique DNA. In both species, repetitive sequences occur in a mixture of long and short period interspersion but most (65–80%) of the DNA follows a pattern of short period interspersion. Genome size and organization in the three tick species so far examined are distinct from other arthropods in having a greater proportion of MR, a lower proportion of unique and HR DNA of very low sequence complexity
Spin measurements for 147Sm+n resonances: Further evidence for non-statistical effects
We have determined the spins J of resonances in the 147Sm(n,gamma) reaction
by measuring multiplicities of gamma-ray cascades following neutron capture.
Using this technique, we were able to determine J values for all but 14 of the
140 known resonances below En = 1 keV, including 41 firm J assignments for
resonances whose spins previously were either unknown or tentative. These new
spin assignments, together with previously determined resonance parameters,
allowed us to extract separate level spacings and neutron strength functions
for J = 3 and 4 resonances. Furthermore, several statistical test of the data
indicate that very few resonances of either spin have been missed below En =
700eV. Because a non-statistical effect recently was reported near En = 350 eV
from an analysis of 147Sm(n,alpha) data, we divided the data into two regions;
0 < En < 350 eV and 350 < En < 700 eV. Using neutron widths from a previous
measurement and published techniques for correcting for missed resonances and
for testing whether data are consistent with a Porter-Thomas distribution, we
found that the reduced-neutron-width distribution for resonances below 350 eV
is consistent with the expected Porter-Thomas distribution. On the other hand,
we found that reduced-neutron-width data in the 350 < En < 700 eV region are
inconsistent with a Porter-Thomas distribution, but in good agreement with a
chi-squared distribution having two or more degrees of freedom. We discuss
possible explanations for these observed non-statistical effects and their
possible relation to similar effects previously observed in other nuclides.Comment: 40 pages, 13 figures, accepted by Phys. Rev.
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