221 research outputs found
Using effective medium theories to design tailored nanocomposite materials for optical systems
Modern optical systems are subject to very restrictive performance, size and
cost requirements. Especially in portable systems size often is the most
important factor, which necessitates elaborate designs to achieve the desired
specifications. However, current designs already operate very close to the
physical limits and further progress is difficult to achieve by changing only
the complexity of the design. Another way of improving the performance is to
tailor the optical properties of materials specifically to the application at
hand. A class of novel, customizable materials that enables the tailoring of
the optical properties, and promises to overcome many of the intrinsic
disadvantages of polymers, are nanocomposites. However, despite considerable
past research efforts, these types of materials are largely underutilized in
optical systems. To shed light into this issue we, in this paper, discuss how
nanocomposites can be modeled using effective medium theories. In the second
part, we then investigate the fundamental requirements that have to be
fulfilled to make nanocomposites suitable for optical applications, and show
that it is indeed possible to fabricate such a material using existing methods.
Furthermore, we show how nanocomposites can be used to tailor the refractive
index and dispersion properties towards specific applications.Comment: This is a draft manuscript of a paper published in Proc. SPIE
(Proceedings Volume 10745, Current Developments in Lens Design and Optical
Engineering XIX, Event: SPIE Optical Engineering + Applications, 2018
Knowledge Graph Representations to enhance Intensive Care Time-Series Predictions
Intensive Care Units (ICU) require comprehensive patient data integration for
enhanced clinical outcome predictions, crucial for assessing patient
conditions. Recent deep learning advances have utilized patient time series
data, and fusion models have incorporated unstructured clinical reports,
improving predictive performance. However, integrating established medical
knowledge into these models has not yet been explored. The medical domain's
data, rich in structural relationships, can be harnessed through knowledge
graphs derived from clinical ontologies like the Unified Medical Language
System (UMLS) for better predictions. Our proposed methodology integrates this
knowledge with ICU data, improving clinical decision modeling. It combines
graph representations with vital signs and clinical reports, enhancing
performance, especially when data is missing. Additionally, our model includes
an interpretability component to understand how knowledge graph nodes affect
predictions.Comment: Extended Abstract presented at Machine Learning for Health (ML4H)
symposium 2023, December 10th, 2023, New Orleans, United States, 11 page
Recovery of 150-250 MeV/nuc Cosmic Ray Helium Nuclei Intensities Between 2004-2010 Near the Earth, at Voyager 2 and Voyager 1 in the Heliosheath - A Two Zone Helioshpere
The recovery of cosmic ray He nuclei of energy ~150-250 MeV/nuc in solar
cycle #23 from 2004 to 2010 has been followed at the Earth using IMP and ACE
data and at V2 between 74-92 AU and also at V1 beyond the heliospheric
termination shock (91-113 AU). The correlation coefficient between the
intensities at the Earth and at V1 during this time period is remarkable
(0.921), after allowing for a ~0.9 year delay due to the solar wind propagation
time from the Earth to the outer heliosphere. To describe the intensity changes
and to predict the absolute intensities measured at all three locations we have
used a simple spherically symmetric (no drift) two-zone heliospheric transport
model with specific values for the diffusion coefficient in both the inner and
outer zones. The diffusion coefficient in the outer zone, assumed to be the
heliosheath from about 90 to 120 (130) AU, is determined to be ~5 times smaller
than that in the inner zone out to 90 AU. This means the Heliosheath acts much
like a diffusing barrier in this model. The absolute magnitude of the
intensities and the intensity changes at V1 and the Earth are described to
within a few percent by a diffusion coefficient that varies with time by a
factor ~4 in the inner zone and only a factor of ~1.5 in the outer zone over
the time period from 2004-2010. For V2 the observed intensities follow a curve
that is as much as 25% higher than the calculated intensities at the V2 radius
and at times the observed V2 intensities are equal to those at V1. At least
one-half of the difference between the calculated and observed intensities
between V1 and V2 can be explained if the heliosphere is squashed by ~10% in
distance (non-spherical) so that the HTS location is closer to the Sun in the
direction of V2 compared to V1.Comment: 13 Pages, 8 Figure
Design rules for customizable optical materials based on nanocomposites
Nanocomposites with tailored optical properties can provide a new degree of
freedom for optical design. However, despite their potential these materials
remain unused in bulk applications. Here we investigate the conditions under
which they can be used for optical applications using Mie theory, effective
medium theories, and numerical simulations based on the finite element method.
We show that due to scattering different effective medium regimes have to be
distinguished, and that bulk materials can only be realized in a specific
parameter range. Our analysis also enables us to quantify the range of validity
of different effective medium theories, and identify design rules on how the
free material parameters should be adjusted for specific applications.Comment: 13 pages, 6 figure
Modeling Optical Materials at the Single Scatterer Level: The Transition from Homogeneous to Heterogeneous Materials
Python FPGA Programming with Data-Centric Multi-Level Design
Although high-level synthesis (HLS) tools have significantly improved
programmer productivity over hardware description languages, developing for
FPGAs remains tedious and error prone. Programmers must learn and implement a
large set of vendor-specific syntax, patterns, and tricks to optimize (or even
successfully compile) their applications, while dealing with ever-changing
toolflows from the FPGA vendors. We propose a new way to develop, optimize, and
compile FPGA programs. The Data-Centric parallel programming (DaCe) framework
allows applications to be defined by their dataflow and control flow through
the Stateful DataFlow multiGraph (SDFG) representation, capturing the abstract
program characteristics, and exposing a plethora of optimization opportunities.
In this work, we show how extending SDFGs with multi-level Library Nodes
incorporates both domain-specific and platform-specific optimizations into the
design flow, enabling knowledge transfer across application domains and FPGA
vendors. We present the HLS-based FPGA code generation backend of DaCe, and
show how SDFGs are code generated for either FPGA vendor, emitting efficient
HLS code that is structured and annotated to implement the desired
architecture
Frequency and intensity of [18F]-PSMA-1007 uptake after COVID-19 vaccination in clinical PET
Objectives: To assess the frequency and intensity of [18F]-prostate-specific membrane antigen (PSMA)-1007 axillary uptake in lymph nodes ipsilateral to COVID-19 vaccination with BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) in patients with prostate cancer referred for oncological [18F]-PSMA positron emission tomography (PET)/CT or PET/MR imaging.
Methods: 126 patients undergoing [18F]-PSMA PET/CT or PET/MR imaging were retrospectively included. [18F]-PSMA activity (maximum standardized uptake value) of ipsilateral axillary lymph nodes was measured and compared with the non-vaccinated contralateral side and with a non-vaccinated negative control group. [18F]-PSMA active lymph node metastases were measured to serve as quantitative reference.
Results: There was a significant difference in maximum standardized uptake value in ipsilateral and compared to contralateral axillary lymph nodes in the vaccination group (n = 63, p < 0.001) and no such difference in the non-vaccinated control group (n = 63, p = 0.379). Vaccinated patients showed mildly increased axillary lymph node [18F]-PSMA uptake as compared to non-vaccinated patients (p = 0.03). [18F]-PSMA activity of of lymph node metastases was significantly higher (p < 0.001) compared to axillary lymph nodes of vaccinated patients.
Conclusion: Our data suggest mildly increased [18F]-PSMA uptake after COVID-19 vaccination in ipsilateral axillary lymph nodes. However, given the significantly higher [18F]-PSMA uptake of prostatic lymph node metastases compared to "reactive" nodes after COVID-19 vaccination, no therapeutic and diagnostic dilemma is to be expected.
Advances in knowledge: No specific preparations or precautions (e.g. adaption of vaccination scheduling) need to be undertaken in patients undergoing [18F]-PSMA PET imaging after COVID-19 vaccination
ErbB2/HER2-specific NK cells for adoptive cancer immunotherapy
Poster presentation: 28th Annual Scientific Meeting of the Society for Immunotherapy of Cancer (SITC)
Significant progress has been made over the last decade towards realizing the potential of natural killer (NK) cells for cancer immunotherapy. NK cells can respond rapidly to transformed and stressed cells, and have the intrinsic potential to extravasate and reach their targets in almost all body tissues. In addition to donor-derived primary NK cells, also continuously expanding cytotoxic cell lines such as NK-92 are being considered for adoptive cancer immunotherapy. High cytotoxicity of NK-92 has previously been shown against malignant cells of hematologic origin in preclinical studies, and general safety of infusion of NK-92 cells has been established in phase I clinical trials. To enhance their therapeutic utility, we genetically modified NK-92 cells to express chimeric antigen receptors (CAR) specific for tumor-associated surface antigens. Such CAR were composed of a tumor-specific scFv antibody fragment fused via hinge and transmembrane domains to intracellular signaling moieties such as CD3 zeta chain, or composite fusion molecules also containing a costimulatory protein domain in addition to CD3 zeta. For development towards clinical applications, here a codon-optimized second generation CAR was constructed that consists of an ErbB2-specific scFv antibody domain fused via a linker to a composite CD28-CD3 zeta signaling domain. GMP-compliant protocols for vector production, lentiviral transduction and expansion of a genetically modified NK-92 single cell clone (NK-92/5.28.z) were established. Functional analysis of NK-92/5.28.z cells revealed high and stable CAR expression, selective cytotoxicity against ErbB2-expressing but otherwise NK-resistant tumor cells of different origins in vitro, as well as homing to ErbB2-expressing tumors in vivo. Furthermore, antigen specificity and selective cytotoxicity of these cells were retained in vivo, resulting in antitumoral activity against subcutaneous and intracranial glioblastoma xenografts in NSG mice. Ongoing work now focuses on the development of these cells for adoptive immunotherapy of ErbB2-positive glioblastoma
Using effective medium theories to design tailored nanocomposite materials for optical systems
Modern optical systems are subject to very restrictive performance, size and cost requirements. Especially in portable systems size often is the most important factor, which necessitates elaborate designs to achieve the desired specifications. However, current designs already operate very close to the physical limits and further progress is difficult to achieve by changing only the complexity of the design. Another way of improving the performance is to tailor the optical properties of materials specifically to the application at hand. A class of novel, customizable materials that enables the tailoring of the optical properties, and promises to overcome many of the intrinsic disadvantages of polymers, are nanocomposites. However, despite considerable past research efforts, these types of materials are largely underutilized in optical systems. To shed light into this issue we, in this paper, discuss how nanocomposites can be modeled using effective medium theories. In the second part, we then investigate the fundamental requirements that have to be fulfilled to make nanocomposites suitable for optical applications, and show that it is indeed possible to fabricate such a material using existing methods. Furthermore, we show how nanocomposites can be used to tailor the refractive index and dispersion properties towards specific applications
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