3,165 research outputs found
Staging of cutaneous melanoma
The American Joint Committee on Cancer (AJCC) staging of cutaneous melanoma is a continuously evolving system. The identification of increasingly more accurate prognostic factors has led to major changes in melanoma staging over the years, and the current system described in this review will likely be modified in the near future. Likewise, application of new imaging techniques has also changed the staging work-up of patients with cutaneous melanoma. Chest and abdominal computed tomography (CT) scanning is most commonly used for evaluation of potential metastatic sites in the lungs, lymph nodes and liver, and is indicated in patients with new symptoms, anaemia, elevated lactate dehydrogenase or a chest X-ray abnormality. CT scans should be restricted to patients with high-risk melanoma (stage IIC, IIIB, IIIC and stage IIIA with a macroscopic sentinel lymph node). Magnetic resonance imaging (MRI) of the brain is a mandatory test in patients with stage IV, optional in stage III and not used in patients with stage I and II disease. Positron emission tomography (PET)/CT is more accurate than CT or MRI alone in the diagnosis of metastases and should complement conventional CT/MRI imaging in the staging work-up of patients who have solitary or oligometastatic disease where surgical resection is most relevant
Strain-induced quantum phase transitions in magic angle graphene
We investigate the effect of uniaxial heterostrain on the interacting phase
diagram of magic-angle twisted bilayer graphene. Using both self-consistent
Hartree-Fock and density-matrix renormalization group calculations, we find
that small strain values () drive a
zero-temperature phase transition between the symmetry-broken Kramers
intervalley-coherent insulator and a nematic semi-metal. The critical strain
lies within the range of experimentally observed strain values, and we
therefore predict that strain is at least partly responsible for the
sample-dependent experimental observations
Efficient simulation of moire materials using the density matrix renormalization group
We present an infinite density-matrix renormalization group (DMRG) study of
an interacting continuum model of twisted bilayer graphene (tBLG) near the
magic angle. Because of the long-range Coulomb interaction and the large number
of orbital degrees of freedom, tBLG is difficult to study with standard DMRG
techniques -- even constructing and storing the Hamiltonian already poses a
major challenge. To overcome these difficulties, we use a recently developed
compression procedure to obtain a matrix product operator representation of the
interacting tBLG Hamiltonian which we show is both efficient and accurate even
when including the spin, valley and orbital degrees of freedom. To benchmark
our approach, we focus mainly on the spinless, single-valley version of the
problem where, at half-filling, we find that the ground state is a nematic
semimetal. Remarkably, we find that the ground state is essentially a k-space
Slater determinant, so that Hartree-Fock and DMRG give virtually identical
results for this problem. Our results show that the effects of long-range
interactions in magic angle graphene can be efficiently simulated with DMRG,
and opens up a new route for numerically studying strong correlation physics in
spinful, two-valley tBLG, and other moire materials, in future work.Comment: corrected a typo in arxiv author lis
High Prevalence of Hypovitaminosis D in Adolescents Attending a Reference Centre for the Treatment of Obesity in Switzerland.
Hypovitaminosis D is common in populations with obesity. This study aimed at assessing (1) the prevalence of hypovitaminosis D and (2) the associations between vitamin D levels and cardiovascular risk factors in adolescents attending a reference centre for the treatment of obesity.
Cross-sectional pilot study conducted in the paediatric obesity unit of the Lausanne university hospital, Switzerland.
Participants were considered eligible if they (1) were aged between 10 to 16.9 years and (2) consulted between 2017 and 2021. Participants were excluded if (1) they lacked vitamin D measurements or (2) the vitamin D measurement was performed one month after the base anthropometric assessment. Hypovitaminosis D was considered if the vitamin D level was <30 ng/mL (<75 nmol/L). Severe obesity was defined as a BMI z-score > 3 SD.
We included 52 adolescents (31% girls, mean age 13 ± 2 years, 33% with severe obesity). The prevalence of hypovitaminosis D was 87.5% in girls and 88.9% in boys. The vitamin D levels were inversely associated with BMI, Spearman r and 95% CI: -0.286 (-0.555; -0.017), p = 0.037; they were not associated with the BMI z-score: -0.052 (-0.327; 0.224), p = 0.713. The vitamin D levels were negatively associated with the parathormone levels (-0.353 (-0.667; -0.039), p = 0.028) and positively associated with the calcium levels (0.385 (0.061; 0.708), p = 0.020), while no association was found between vitamin D levels and blood pressure and lipid or glucose levels.
almost 9 out of 10 adolescents with obesity in our cohort presented with hypovitaminosis D. Hypovitaminosis D does not seem to be associated with a higher cardiovascular risk profile in this group
Growth modes of Fe(110) revisited: a contribution of self-assembly to magnetic materials
We have revisited the epitaxial growth modes of Fe on W(110) and Mo(110), and
propose an overview or our contribution to the field. We show that the
Stranski-Krastanov growth mode, recognized for a long time in these systems, is
in fact characterized by a bimodal distribution of islands for growth
temperature in the range 250-700°C. We observe firstly compact islands
whose shape is determined by Wulff-Kaischev's theorem, secondly thin and flat
islands that display a preferred height, ie independant from nominal thickness
and deposition procedure (1.4nm for Mo, and 5.5nm for W on the average). We
used this effect to fabricate self-organized arrays of nanometers-thick stripes
by step decoration. Self-assembled nano-ties are also obtained for nucleation
of the flat islands on Mo at fairly high temperature, ie 800°C. Finally,
using interfacial layers and solid solutions we separate two effects on the
preferred height, first that of the interfacial energy, second that of the
continuously-varying lattice parameter of the growth surface.Comment: 49 pages. Invited topical review for J. Phys.: Condens. Matte
Biomarkers in melanoma
Biomarkers are tumour- or host-related factors that correlate with tumour biological behaviour and patient prognosis. High-throughput analytical techniques--DNA and RNA microarrays--have identified numerous possible biomarkers, but their relevance to melanoma progression, clinical outcome and the selection of optimal treatment strategies still needs to be established. The review discusses a possible molecular basis for predictive tissue biomarkers such as melanoma thickness, ulceration and mitotic activity, and provides a list of promising new biomarkers identified from tissue microarrays that needs confirmation by independent, prospectively collected clinical data sets. In addition, common predictive serum biomarkers--lactate dehydrogenase, S100B and melanoma-inhibiting activity--as well as selected investigational serum biomarkers such as TA90IC and YKL-40 are also reviewed. A more accurate, therapeutically predictive classification of human melanomas and selection of patient populations that would profit from therapeutic interventions are among the major challenges expected to be addressed in the futur
Biomarkers in melanoma
Biomarkers are tumour- or host-related factors that correlate with tumour biological behaviour and patient prognosis. High-throughput analytical techniques—DNA and RNA microarrays—have identified numerous possible biomarkers, but their relevance to melanoma progression, clinical outcome and the selection of optimal treatment strategies still needs to be established. The review discusses a possible molecular basis for predictive tissue biomarkers such as melanoma thickness, ulceration and mitotic activity, and provides a list of promising new biomarkers identified from tissue microarrays that needs confirmation by independent, prospectively collected clinical data sets. In addition, common predictive serum biomarkers—lactate dehydrogenase, S100B and melanoma-inhibiting activity—as well as selected investigational serum biomarkers such as TA90IC and YKL-40 are also reviewed. A more accurate, therapeutically predictive classification of human melanomas and selection of patient populations that would profit from therapeutic interventions are among the major challenges expected to be addressed in the future
Readout of GEM Detectors Using the Medipix2 CMOS Pixel Chip
We have operated a Medipix2 CMOS readout chip, with amplifying, shaping and
charge discriminating front-end electronics integrated on the pixel-level, as a
highly segmented direct charge collecting anode in a three-stage gas electron
multiplier (Triple-GEM) to detect the ionization from Fe X-rays and
electrons from Ru. The device allows to perform moderate energy
spectroscopy measurements (20 % FWHM at 5.9 keV -rays) using only digital
readout and two discriminator thresholds. Being a truly 2D-detector, it allows
to observe individual clusters of minimum ionizing charged particles in
(70:30) and (70:30) mixtures and to achieve excellent
spatial resolution for position reconstruction of primary clusters down to
, based on the binary centroid determination method.Comment: 18 pages, 14 pictures. submitted to Nuclear Instruments and Methods
in Physics Research
Kekul\'e spiral order in magic-angle graphene: a density matrix renormalization group study
When the two layers of a twisted moir\'e system are subject to different
degrees of strain, the effect is amplified by the inverse twist angle, e.g., by
a factor of 50 in magic angle twisted bilayer graphene (TBG). Samples of TBG
typically have heterostrains of 0.1-0.7%, increasing the bandwidth of the
"flat'' bands by as much as tenfold, placing TBG in an intermediate coupling
regime. Here we study the phase diagram of TBG in the presence of heterostrain
with unbiased, large-scale density matrix renormalization group calculations
(bond dimension ), including all spin and valley degrees of
freedom. Working at filling , we find a strain of drives a
transition from a quantized anomalous Hall insulator into an
incommensurate-Kekul\'e spiral (IKS) phase. This peculiar order, proposed and
studied at mean-field level by Kwan et al (PRX 11, 041063), breaks both valley
conservation and translation symmetry , but preserves a modified
translation symmetry with moir\'e-incommensurate phase modulation.
Even higher strains drive the system to a fully symmetric metal.Comment: 4.5 pages and three figures, plus appendice
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