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Mapping tumour tissue: quantitative maps of histological whole slide images
Cyclotron resonance of the quasi-two-dimensional electron gas at Hg1-xCdxTe grain boundaries
The magnetotransmission of a p-type Hg0.766Cd0.234Te bicrystal containing a single grain boundary with an inversion layer has been investigated in the submillimetre wavelength range. For the first time the cyclotron resonance lines belonging to the various electric subbands of a quasi-two-dimensional carrier system at a grain boundary could be detected. The measured cyclotron masses and the subband densities determined from Shubnikov-de Haas experiments are compared with theoretical predictions and it is found that the data can be explained very well within the framework of a triangular well approximation model which allows for non-parabolic effects
Simultaneous observations of NLCs and MSEs at midlatitudes: implications for formation and advection of ice particles
We combined ground-based lidar observations of noctilucent clouds (NLCs) with
collocated, simultaneous radar observations of mesospheric summer echoes
(MSEs) in order to compare ice cloud altitudes at a midlatitude site
(Kühlungsborn, Germany, 54° N, 12° E). Lidar
observations are limited to larger particles ( > 10 nm), while radars are
also sensitive to small particles ( < 10 nm), but require sufficient
ionization and turbulence at the ice cloud altitudes. The combined lidar and
radar data set thus includes some information on the size distribution within
the cloud and through this on the history of the cloud. The soundings for this
study are carried out by the IAP Rayleigh–Mie–Raman (RMR) lidar and the OSWIN VHF radar. On
average, there is no difference between the lower edges
(zlowNLC and zlowMSE). The mean
difference of the upper edges zupNLC and
zupMSE is ∼ 500 m, which is much less than
expected from observations at higher latitudes. In contrast to high
latitudes, the MSEs above our location typically do not reach much higher than
the NLCs. In addition to earlier studies from our site, this gives additional
evidence for the supposition that clouds containing large enough particles to
be observed by lidar are not formed locally but are advected from higher
latitudes. During the advection process, the smaller particles in the upper
part of the cloud either grow and sediment, or they sublimate. Both processes
result in a thinning of the layer. High-altitude MSEs, usually indicating
nucleation of ice particles, are rarely observed in conjunction with lidar
observations of NLCs at Kühlungsborn.</p
Multi-electron giant dipole resonances of atoms in crossed electric and magnetic fields
Multi-electron giant dipole resonances of atoms in crossed electric and
magnetic fields are investigated. Stationary configurations corresponding to a
highly symmetric arrangement of the electrons on a decentered circle are
derived, and a normal-mode stability analysis is performed. A classification of
the various modes, which are dominated either by the magnetic or Coulomb
interactions, is provided. A six-dimensional wave-packet dynamical study, based
on the MCTDH approach, is accomplished for the two-electron resonances,
yielding in particular lifetimes of more than 0.1 s for strong electric
fields.Comment: 7 pages, 3 figure
Generation of annotated multimodal ground truth datasets for abdominal medical image registration
Sparsity of annotated data is a major limitation in medical image processing
tasks such as registration. Registered multimodal image data are essential for
the diagnosis of medical conditions and the success of interventional medical
procedures. To overcome the shortage of data, we present a method that allows
the generation of annotated multimodal 4D datasets. We use a CycleGAN network
architecture to generate multimodal synthetic data from the 4D extended
cardiac-torso (XCAT) phantom and real patient data. Organ masks are provided by
the XCAT phantom, therefore the generated dataset can serve as ground truth for
image segmentation and registration. Realistic simulation of respiration and
heartbeat is possible within the XCAT framework. To underline the usability as
a registration ground truth, a proof of principle registration is performed.
Compared to real patient data, the synthetic data showed good agreement
regarding the image voxel intensity distribution and the noise characteristics.
The generated T1-weighted magnetic resonance imaging (MRI), computed tomography
(CT), and cone beam CT (CBCT) images are inherently co-registered. Thus, the
synthetic dataset allowed us to optimize registration parameters of a
multimodal non-rigid registration, utilizing liver organ masks for evaluation.
Our proposed framework provides not only annotated but also multimodal
synthetic data which can serve as a ground truth for various tasks in medical
imaging processing. We demonstrated the applicability of synthetic data for the
development of multimodal medical image registration algorithms.Comment: 12 pages, 5 figures. This work has been published in the
International Journal of Computer Assisted Radiology and Surgery volum
Bose-Hubbard model with occupation dependent parameters
We study the ground-state properties of ultracold bosons in an optical
lattice in the regime of strong interactions. The system is described by a
non-standard Bose-Hubbard model with both occupation-dependent tunneling and
on-site interaction. We find that for sufficiently strong coupling the system
features a phase-transition from a Mott insulator with one particle per site to
a superfluid of spatially extended particle pairs living on top of the Mott
background -- instead of the usual transition to a superfluid of single
particles/holes. Increasing the interaction further, a superfluid of particle
pairs localized on a single site (rather than being extended) on top of the
Mott background appears. This happens at the same interaction strength where
the Mott-insulator phase with 2 particles per site is destroyed completely by
particle-hole fluctuations for arbitrarily small tunneling. In another regime,
characterized by weak interaction, but high occupation numbers, we observe a
dynamical instability in the superfluid excitation spectrum. The new ground
state is a superfluid, forming a 2D slab, localized along one spatial direction
that is spontaneously chosen.Comment: 16 pages, 4 figure
Consensus-Based Technical Recommendations for Clinical Translation of Renal Phase Contrast MRI
BACKGROUND:
Phase-contrast (PC) MRI is a feasible and valid noninvasive technique to measure renal artery blood flow, showing potential to support diagnosis and monitoring of renal diseases. However, the variability in measured renal blood flow values across studies is large, most likely due to differences in PC-MRI acquisition and processing. Standardized acquisition and processing protocols are therefore needed to minimize this variability and maximize the potential of renal PC-MRI as a clinically useful tool.
PURPOSE:
To build technical recommendations for the acquisition, processing, and analysis of renal 2D PC-MRI data in human subjects to promote standardization of renal blood flow measurements and facilitate the comparability of results across scanners and in multicenter clinical studies.
STUDY TYPE:
Systematic consensus process using a modified Delphi method.
POPULATION:
Not applicable.
SEQUENCE FIELD/STRENGTH:
Renal fast gradient echo-based 2D PC-MRI.
ASSESSMENT:
An international panel of 27 experts from Europe, the USA, Australia, and Japan with 6 (interquartile range 4–10) years of experience in 2D PC-MRI formulated consensus statements on renal 2D PC-MRI in two rounds of surveys. Starting from a recently published systematic review article, literature-based and data-driven statements regarding patient preparation, hardware, acquisition protocol, analysis steps, and data reporting were formulated.
STATISTICAL TESTS:
Consensus was defined as ≥75% unanimity in response, and a clear preference was defined as 60–74% agreement among the experts.
RESULTS:
Among 60 statements, 57 (95%) achieved consensus after the second-round survey, while the remaining three showed a clear preference. Consensus statements resulted in specific recommendations for subject preparation, 2D renal PC-MRI data acquisition, processing, and reporting.
DATA CONCLUSION:
These recommendations might promote a widespread adoption of renal PC-MRI, and may help foster the set-up of multicenter studies aimed at defining reference values and building larger and more definitive evidence, and will facilitate clinical translation of PC-MRI.
LEVEL OF EVIDENCE:
1
TECHNICAL EFFICACY STAGE:
Repulsive polarons and itinerant ferromagnetism in strongly polarized Fermi gases
We analyze the properties of a single impurity immersed in a Fermi sea. At
positive energy and scattering lengths, we show that the system possesses a
well-defined but metastable excitation, the repulsive polaron, and we calculate
its energy, quasiparticle residue and effective mass. From a thermodynamic
argument we obtain the number of particles in the dressing cloud, illustrating
the repulsive character of the polaron. Identifying the important 2- and 3-body
decay channels, we furthermore calculate the lifetime of the repulsive polaron.
The stability conditions for the formation of fully spin polarized
(ferromagnetic) domains are then examined for a binary mixture of atoms with a
general mass ratio. Our results indicate that mass imbalance lowers the
critical interaction strength for phase-separation, but that very short
quasiparticle decay times will complicate the experimental observation of
itinerant ferromagnetism. Finally, we present the spectral function of the
impurity for various coupling strengths and momenta.Comment: Substantial improvements to the section describing quasiparticle
decays (included a discussion of two-body and three-body processes), and to
the criteria for the stability of the itinerant ferromagnetic phas
Work-related allergy in medical doctors: atopy, exposure to domestic animals, eczema induced by common chemicals and membership of the surgical profession as potential risk factors
Purpose To investigate the risk factors associated with
work-related allergy-like symptoms in medical doctors.
Methods Self-administered questionnaire survey and CAP
test were conducted among medical school students in the
4th grade of their 6-year medical course in 1993–1996 and
1999–2001. Follow-up questionnaires were sent in 2004 to
the graduates. These questionnaires enquired into personal
and family history of allergic diseases, lifestyle, history of
allergy-like symptoms including work-relatedness and
occupational history as medical doctors. Relationships
between allergy-like symptoms and relevant factors were
evaluated by multivariate logistic regression analysis.
Results Of 261 respondents at the follow-up survey, 139
(53.3%) and 54 (20.7%) had a history of any allergy-like
symptoms and any work-related allergy-like symptoms,
respectively. Female gender and family history of allergic
diseases were signiWcantly associated with any allergy-like
symptoms. Personal history of allergic disease, exposure
to domestic animals, eczema caused by rubber gloves,
metallic accessories, or cosmetics during schooling days,
and membership of the surgical profession were signiW-
cant risk factors for work-related allergy-like symptoms.
On the contrary, to work-related allergy-like symptoms,
gender, age, and smoking status were not signiWcantly
related, and consumption of prepared foods was inversely
related.
Conclusions Personal history of atopy and eczema
induced by common goods and the history of keeping
domestic animals may be predictors of work-related
allergy-like symptoms in doctors. After graduation from
medical school, physicians start with exposure to various
allergens and irritants at work, which relate to work-related
allergy-like symptoms, especially for surgeons
Stable isotope dilution assay for the accurate determination of mycotoxins in maize by UHPLC-MS/MS
A fast, easy-to-handle and cost-effective analytical method for 11 mycotoxins currently regulated in maize and other cereal-based food products in Europe was developed and validated for maize. The method is based on two extraction steps using different acidified acetonitrile–water mixtures. Separation is achieved using ultrahigh-performance liquid chromatography (UHPLC) by a linear water–methanol gradient. After electrospray ionisation, tandem mass spectrometric detection is performed in dynamic multiple reaction monitoring mode. Since accurate mass spectrometric quantification is hampered by matrix effects, uniformly [13C]-labelled mycotoxins for each of the 11 compounds were added to the sample extracts prior to UHPLC-MS/MS analysis. Method performance parameters were obtained by spiking blank maize samples with mycotoxins before as well as after extraction on six levels in triplicates. The twofold extraction led to total recoveries of the extraction steps between 97% and 111% for all target analytes, including fumonisins. The [13C]-labelled internal standards efficiently compensated all matrix effects in electrospray ionisation, leading to apparent recoveries between 88% and 105% with reasonable additional costs. The relative standard deviations of the whole method were between 4% and 11% for all analytes. The trueness of the method was verified by the measurement of several maize test materials with well-characterized concentrations. In conclusion, the developed method is capable of determining all regulated mycotoxins in maize and presuming similar matrix effects and extraction recovery also in other cereal-based foods
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