1,764 research outputs found
Phenotypic robustness can increase phenotypic variability after non-genetic perturbations in gene regulatory circuits
Non-genetic perturbations, such as environmental change or developmental
noise, can induce novel phenotypes. If an induced phenotype confers a fitness
advantage, selection may promote its genetic stabilization. Non-genetic
perturbations can thus initiate evolutionary innovation. Genetic variation that
is not usually phenotypically visible may play an important role in this
process. Populations under stabilizing selection on a phenotype that is robust
to mutations can accumulate such variation. After non-genetic perturbations,
this variation can become a source of new phenotypes. We here study the
relationship between a phenotype's robustness to mutations and a population's
potential to generate novel phenotypic variation. To this end, we use a
well-studied model of transcriptional regulation circuits. Such circuits are
important in many evolutionary innovations. We find that phenotypic robustness
promotes phenotypic variability in response to non-genetic perturbations, but
not in response to mutation. Our work suggests that non-genetic perturbations
may initiate innovation more frequently in mutationally robust gene expression
traits.Comment: 11 pages, 5 figure
Lung Nodules in Melanoma Patients: Morphologic Criteria to Differentiate Non-Metastatic and Metastatic Lesions
Lung nodules are frequent findings in chest computed tomography (CT) in patients with metastatic melanoma. In this study, we assessed the frequency and compared morphologic differences of metastases and benign nodules. We retrospectively evaluated 85 patients with melanoma (AJCC stage III or IV). Inclusion criteria were ≤20 lung nodules and follow-up using CT ≥183 days after baseline. Lung nodules were evaluated for size and morphology. Nodules with significant growth, nodule regression in line with RECIST assessment or histologic confirmation were judged to be metastases. A total of 438 lung nodules were evaluated, of which 68% were metastases. At least one metastasis was found in 78% of patients. A 10 mm diameter cut-off (used for RECIST) showed a specificity of 95% and a sensitivity of 20% for diagnosing metastases. Central location (n = 122) was more common in metastatic nodules (p = 0.009). Subsolid morphology (n = 53) was more frequent (p < 0.001), and calcifications (n = 13) were solely found in non-metastatic lung nodules (p < 0.001). Our data show that lung nodules are prevalent in about two-thirds of melanoma patients (AJCC stage III/IV) and the majority are metastases. Even though we found a few morphologic indicators for metastatic or non-metastatic lung nodules, morphology has limited value to predict the presence of lung metastases
Conclusive quantum steering with superconducting transition edge sensors
Quantum steering allows two parties to verify shared entanglement even if one
measurement device is untrusted. A conclusive demonstration of steering through
the violation of a steering inequality is of considerable fundamental interest
and opens up applications in quantum communication. To date all experimental
tests with single photon states have relied on post-selection, allowing
untrusted devices to cheat by hiding unfavourable events in losses. Here we
close this "detection loophole" by combining a highly efficient source of
entangled photon pairs with superconducting transition edge sensors. We achieve
an unprecedented ~62% conditional detection efficiency of entangled photons and
violate a steering inequality with the minimal number of measurement settings
by 48 standard deviations. Our results provide a clear path to practical
applications of steering and to a photonic loophole-free Bell test.Comment: Preprint of 7 pages, 3 figures; the definitive version is published
in Nature Communications, see below. Also, see related experimental work by
A. J. Bennet et al., arXiv:1111.0739 and B. Wittmann et al., arXiv:1111.076
Performance Analysis of High Temperature Heat Pump Cycle for Industrial Process
High-temperature heat pumps (HTHP) that can supply heat at temperatures above 200 °C have a very large potential to enhance the energy efficiency of the industrial sector and reduce its CO2 emissions. In the current work, the thermodynamic performance of three different vapor compression cycles, which use R-718 (water) as a working medium, have been evaluated using a commercial process simulation tool (EBSILON Professional 15). All considered cycles use two-stage vapor compression with different intercooling strategies
between the stages and the thermodynamic performances of those cycles have been investigated.
The comparison studies on the coefficient of performance (COP) and heat supply temperatures have been conducted for all cycle architectures. With increasing temperature difference between a heat
source and heat sink, ∆T, the COP values decreased as expected. The highest COP value was found for the cycle configurations where both compressors have the same pressure ratio (PR).
The investigation on the HTHP capacities and exergy efficiency, ηexergy, with optimized PR has also been carried out. Both COP and ηexergy values increased with decreasing ∆T and the intercooler cycles with heat exchanger showed higher COP and ηexergy than the spray injection cycle
Criteria for the use of omics-based predictors in clinical trials.
The US National Cancer Institute (NCI), in collaboration with scientists representing multiple areas of expertise relevant to 'omics'-based test development, has developed a checklist of criteria that can be used to determine the readiness of omics-based tests for guiding patient care in clinical trials. The checklist criteria cover issues relating to specimens, assays, mathematical modelling, clinical trial design, and ethical, legal and regulatory aspects. Funding bodies and journals are encouraged to consider the checklist, which they may find useful for assessing study quality and evidence strength. The checklist will be used to evaluate proposals for NCI-sponsored clinical trials in which omics tests will be used to guide therapy
Chiral dynamics of p-wave in K^- p and coupled states
We perform an evaluation of the p-wave amplitudes of meson-baryon scattering
in the strangeness S=-1 sector starting from the lowest order chiral
Lagrangians and introducing explicitly the Sigma^* field with couplings to the
meson-baryon states obtained using SU(6) symmetry. The N/D method of
unitarization is used, equivalent, in practice, to the use of the
Bethe-Salpeter equation with a cut-off. The procedure leaves no freedom for the
p-waves once the s-waves are fixed and thus one obtains genuine predictions for
the p-wave scattering amplitudes, which are in good agreement with experimental
results for differential cross sections, as well as for the width and partial
decay widths of the Sigma^*(1385).Comment: LaTeX, 18 pages, 6 figure
Bell inequalities for entangled kaons and their unitary time evolution
We investigate Bell inequalities for neutral kaon systems from Phi resonance
decay to test local realism versus quantum mechanics. We emphasize the unitary
time evolution of the states, that means we also include all decay product
states, in contrast to other authors. Only this guarantees the use of the
complete Hilbert space. We develop a general formalism for Bell inequalities
including both arbitrary "quasi spin" states and different times; finally we
analyze Wigner-type inequalities. They contain an additional term, a correction
function h, as compared to the spin 1/2 or photon case, which changes
considerably the possibility of quantum mechanics to violate the Bell
inequality. Examples for special "quasi spin" states are given, especially
those which are sensitive to the CP parameters epsilon and epsilon'.Comment: REVTeX, 22 page
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