5,743 research outputs found
Direct 3D Tomographic Reconstruction and Phase-Retrieval of Far-Field Coherent Diffraction Patterns
We present an alternative numerical reconstruction algorithm for direct
tomographic reconstruction of a sample refractive indices from the measured
intensities of its far-field coherent diffraction patterns. We formulate the
well-known phase-retrieval problem in ptychography in a tomographic framework
which allows for simultaneous reconstruction of the illumination function and
the sample refractive indices in three dimensions. Our iterative reconstruction
algorithm is based on the Levenberg-Marquardt algorithm. We demonstrate the
performance of our proposed method with simulation studies
Second Overtone Pulsators Among Delta Scuti Stars
We investigate the modal stability of stellar models at masses and luminosity
levels corresponding to post main sequence luminous delta scuti pulsators. The
envelope models have been computed at fixed mass value, luminosity level and
chemical composition (Y=0.28, Z=0.02). According to a nonlinear approach to
radial oscillations the present investigation predicts the occurrence of stable
second overtone pulsators for the first time. The shape of both light and
velocity curves are presented and discussed, providing a useful tool for the
identification of second overtone pulsators among the known groups of radially
pulsating stars. The period ratios of mixed mode pulsators obtained by
perturbing the first and the second overtone radial eigenfunctions are in
agreement with observative values. Finally, the physical structure and the
dynamical properties of second overtone pulsators are discussed in detail. The
role played by the nodal lines in the destabilization of second overtone
pulsators is also pointed out.Comment: 20 pages, 11 Postscript figures, uses aaspp4.sty and tighten.st
Design of organic Rankine cycles using a non-conventional optimization approach
The organic Rankine cycle is a suitable technology for utilizing low grade heat for electricity production. Compared to the traditional steam Rankine cycle, the organic Rankine cycle is beneficial, since it enables the choice of a working fluid which performs better than steam at low heat input temperatures and at lowpower outputs. Selecting the process layout of the organic Rankine cycle and the working fluid are two key design decisions which are critical for the thermodynamic and economic performance of the cycle. The prevailing approach used in the design and optimization of organic Rankine cycles is to model the heatexchangers by assuming a fixed minimum temperature difference. The objective of this work is to assess the applicability of this conventional optimization approach and a non-conventional optimization approach. In thenon-conventional optimization approach a total UA-value (the product of the overall heat transfer coefficient and the heat transfer area) is assigned to the cycle, while the distribution of this total UA-value to each of the heat exchangers is optimized. Optimizations are carried out for three different marine engine waste heatsources at temperatures ranging from 90 °C to 285 °C. The results suggest that the conventional optimization approach is not suitable for estimating the performance potential when the temperature profiles in the heat exchangers are closely matched. This is exemplified for the fluid MDM where the temperature profile of preheating aligns with the heat source fluid and for the zeotropic mixture R32/R134a where the temperature profile of condensation aligns with the cooling water. Furthermore, the conventional optimization approach shows weaknesses in evaluating the feasibility of using a recuperator, when the expander outlet temperature is high. In these cases the non-conventional optimization approach is the more suited methodology for designing organic Rankine cycles
Deep Learning-based Anomaly Detection on X-ray Images of Fuel Cell Electrodes
Anomaly detection in X-ray images has been an active and lasting research
area in the last decades, especially in the domain of medical X-ray images. For
this work, we created a real-world labeled anomaly dataset, consisting of
16-bit X-ray image data of fuel cell electrodes coated with a platinum catalyst
solution and perform anomaly detection on the dataset using a deep learning
approach. The dataset contains a diverse set of anomalies with 11 identified
common anomalies where the electrodes contain e.g. scratches, bubbles, smudges
etc. We experiment with 16-bit image to 8-bit image conversion methods to
utilize pre-trained Convolutional Neural Networks as feature extractors
(transfer learning) and find that we achieve the best performance by maximizing
the contrasts globally across the dataset during the 16-bit to 8-bit
conversion, through histogram equalization. We group the fuel cell electrodes
with anomalies into a single class called abnormal and the normal fuel cell
electrodes into a class called normal, thereby abstracting the anomaly
detection problem into a binary classification problem. We achieve a balanced
accuracy of 85.18\%. The anomaly detection is used by the company, Serenergy,
for optimizing the time spend on the quality control of the fuel cell
electrodesComment: 10 pages, 9 figures, VISAPP202
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Novel mutation in CCBE 1 as a cause of recurrent hydrops fetalis from Hennekam lymphangiectasia-lymphedema syndrome-1.
Whole exome sequencing (WES) was used to determine the etiology of recurrent hydrops fetalis in this case of Hennekam lymphangiectasia-lymphedema syndrome-1. WES is a useful approach for diagnosing rare single-gene conditions with nonspecific phenotypes and should be considered early in the diagnostic process of investigating fetal abnormalities
NA0D – The new traumatic dental injury classification of the world health organization
An accurate, clear, and easy-to-
use
traumatic dental injury (TDI) classification and definition
system is a prerequisite for proper diagnosis, study, and treatment. However,
more than 50 classifications have been used in the past. The ideal solution would be
that TDIs are adequately classified within the International Classification of Diseases
(ICD), endorsed by the World Health Organization (WHO). TDI classification provided
by the 11th Revision of the ICD (ICD-11),
released in 2018, and previous Revisions,
failed to classify TDIs satisfactorily. Therefore, in December 2018, a proposal was submitted
by Dr's Stefano Petti, Jens Ove Andreasen, Ulf Glendor, and Lars Andersson, to
the ICD-11,
asking for a change of the existing TDI classification. Proposal #2130 highlighted
the TDI paradox, the fifth most frequent disease/condition neglected by most
public health agencies in the world, and the limits of ICD-11
classification. Namely,
injuries of teeth and periodontal tissues were located in two separate blocks that did
not mention dental/periodontal tissues; infraction, concussion, and subluxation were
not coded; most TDIs lacked description; and tooth fractures were described through
bone fracture descriptions (e.g., comminuted, compression, and fissured fractures).
These limitations led to TDI mis-reporting,
under-reporting,
and non-specific
reporting
by untrained non-dental
healthcare providers. In addition, no scientific articles on
TDIs, present in PubMed, Scopus, and Web-of-
Science,
used the ICD classification.
Proposal #2130 suggested to adopt the Andreasen classification, the most widely
acknowledged classification used in dental traumatology. The Proposal was reviewed
by two WHO teams, two scientific Committees, one WHO Collaborating Center, and
the Department of Non-Communicable
Disease Prevention at WHO headquarters,
and it underwent two voting sessions. In March 2022, the Andreasen classification
was accepted integrally. A new entity was generated, called NA0D, “Injury of teeth
or supporting structures” (https://icd.who.int/brows e11/l-m/
en#/http://id.
who.int/icd /ent ity/141 3338122). Hopefully, this will contribute to increasing
the public awareness, and the dental profession's management, of TDIs
HIV Infection among Young People in Northwest Tanzania: The Role of Biological, Behavioural and Socio-Demographic Risk Factors.
BACKGROUND: Young people are at high risk of HIV and developing appropriate prevention programmes requires an understanding of the risk factors for HIV in this age group. We investigated factors associated with HIV among participants aged 15-30 years in a 2007-8 cross-sectional survey nested within a community-randomised trial of the MEMA kwa Vijana intervention in 20 rural communities in northwest Tanzania. METHODS: We analysed data for 7259(53%) males and 6476(47%) females. Using a proximate-determinant conceptual framework and conditional logistic regression, we obtained sex-specific Odds Ratios (ORs) for the association of HIV infection with socio-demographic, knowledge, behavioural and biological factors. RESULTS: HSV-2 infection was strongly associated with HIV infection (females: adjOR 4.4, 95%CI 3.2-6.1; males: adjOR 4.2, 95%CI 2.8-6.2). Several socio-demographic factors (such as age, marital status and mobility), behavioural factors (condom use, number and type of sexual partnerships) and biological factors (blood transfusion, lifetime pregnancies, genital ulcers, Neisseria gonorrhoeae) were also associated with HIV infection. Among females, lifetime sexual partners (linear trend, p<0.001), ≥2 partners in the past year (adjOR 2.0, 95%CI 1.4-2.8), ≥2 new partners in the past year (adjOR 1.9 95%CI 1.2, 3.3) and concurrent partners in the past year (adjOR 1.6 95%CI 1.1, 2.4) were all associated with HIV infection. CONCLUSIONS: Efforts must be intensified to find effective interventions to reduce HSV-2. Effective behavioural interventions focusing on reducing the number of sexual partnerships and risk behaviour within partnerships are also needed. An increase in risky sexual behaviour may occur following marriage dissolution or when a young woman travels outside of her community and interventions addressing the needs of these subgroups of vulnerable women may be important. TRIAL REGISTRATION: ClinicalTrial.gov NCT00248469
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