Adaptive Tuning of Feedback Gain in Time-Delayed Feedback Control

We demonstrate that time-delayed feedback control can be improved by adaptively tuning the feedback gain. This adaptive controller is applied to the stabilization of an unstable fixed point and an unstable periodic orbit embedded in a chaotic attractor. The adaptation algorithm is constructed using the speed-gradient method of control theory. Our computer simulations show that the adaptation algorithm can find an appropriate value of the feedback gain for single and multiple delays. Furthermore, we show that our method is robust to noise and different initial conditions.Comment: 7 pages, 6 figure

The Magellanic Stream and the density of coronal gas in the Galactic halo

The properties of the Magellanic Stream constrain the density of coronal gas in the distant Galactic halo. We show that motion through ambient gas can strongly heat Stream clouds, driving mass loss and causing evaporation. If the ambient gas density is too high, then evaporation occurs on unreasonably short timescales. Since heating dominates drag, tidal stripping appears to be responsible for producing the Stream. Requiring the survival of the cloud MS IV for 500 Myr sets an upper limit on the halo gas density n_H< 10^{-5} cm^{-3} at 50 kpc, roughly a factor of 10 lower than that estimated from the drag model of Moore & Davis (1994). Implications for models of the evolution of gas in galaxy halos are discussed.Comment: 4 pages, 1 figure, in press, ApJ

Defining Rules for Kinematic Shapes with Variable Spatial Relations

Designing mechanisms can be a challenging problem, because the underlying kinematics involved are typically not intuitively incorporated into common techniques for design representation. Kinematic shapes and kinematic grammars build on the shape grammar and making grammar formalisms to enable a visually intuitive approach to model and explore mechanisms. With reference to the lower kinematic pairs this paper introduces kinematic shapes. These are connected shapes with parts which have variable spatial relations that account for the relative motion of the parts. The paper considers how such shapes can be defined, the role of elements shared by connected parts, and the motions that result. It also considers how kinematic shape rules can be employed to generate and explore the motion of mechanisms

Anti-CTLA-4 therapy for malignant mesothelioma

Immunotherapy is an emerging therapeutic strategy with a promising clinical outcome in some solid tumors, particularly metastatic melanoma. One approach to immunotherapy is immune checkpoint inhibitors, such as blockage of CTLA-4 and PD-1/PD-L1. This special report aims to describe the state of clinical trials of tremelimumab in patients with unresectable malignant mesothelioma (MM) in particular with regard to the clinical efficacy, safety and tolerability. Criticism and perspective of this treatment are also discussed. Biological and clinical considerations rule out the use of tremelimumab as single agent for MM and, more generally, the use of immune checkpoint inhibitors for MM is still largely questionable and not supported by evidences

Protein disulfide isomerase A1 regulates breast cancer cell immunorecognition in a manner dependent on redox state

Oxidoreductase protein disulphide isomerases (PDI) are involved in the regulation of a variety of biological processes including the modulation of endoplasmic reticulum (ER) stress, unfolded protein response (UPR), ER‑mitochondria communication and the balance between pro‑survival and pro‑death pathways. In the current study the role of the PDIA1 family member in breast carcinogenesis was investigated by measuring ROS generation, mitochondrial membrane disruption, ATP production and HLA‑G protein levels on the surface of the cellular membrane in the presence or absence of PDIA1. The results showed that this enzyme exerted pro‑apoptotic effects in estrogen receptor (ERα)‑positive breast cancer MCF‑7 and pro‑survival in triple negative breast cancer (TNBC) MDA‑MB‑231 cells. ATP generation was upregulated in PDIA1‑silenced MCF‑7 cells and downregulated in PDIA1‑silenced MDA‑MB‑231 cells in a manner dependent on the cellular redox status. Furthermore, MCF‑7 and MDA‑MB‑231 cells in the presence of PDIA1 expressed higher surface levels of the non‑classical human leukocyte antigen (HLA‑G) under oxidative stress conditions. Evaluation of the METABRIC datasets showed that low PDIA1 and high HLA‑G mRNA expression levels correlated with longer survival in both ERα‑positive and ERα‑negative stage 2 breast cancer patients. In addition, analysis of the PDIA1 vs. the HLA‑G mRNA ratio in the subgroup of the living stage 2 breast cancer patients exhibiting low PDIA1 and high HLA‑G mRNA levels revealed that the longer the survival time of the ratio was high PDIA1 and low HLA‑G mRNA and occurred predominantly in ERα‑positive breast cancer patients whereas in the same subgroup of the ERα‑negative breast cancer mainly this ratio was low PDIA1 and high HLA‑G mRNA. Taken together these results provide evidence supporting the view that PDIA1 is linked to several hallmarks of breast cancer pathways including the process of antigen processing and presentation and tumor immunorecognition

A classical Over Barrier Model to compute charge exchange between ions and one-optical-electron atoms

In this paper we study theoretically the process of electron capture between one-optical-electron atoms (e.g. hydrogenlike or alkali atoms) and ions at low-to-medium impact velocities (v/v_e <= 1) working on a modification of an already developed classical Over Barrier Model (OBM) [V. Ostrovsky, J. Phys. B: At. Mol. Opt. Phys. {\bf 28} 3901 (1995)], which allows to give a semianalytical formula for the cross sections. The model is discussed and then applied to a number of test cases including experimental data as well as data coming from other sophisticated numerical simulations. It is found that the accuracy of the model, with the suggested corrections and applied to quite different situations, is rather high.Comment: 12 pages REVTEX, 5 EPSF figures, submitted to Phys Rev

Source of lead in Central American and Caribbean mineralization, II. Lead isotope provinces

In an earlier study of Mesozoic and Cenozoic mineralization in Central America and the Caribbean region, we found that lead isotopic compositions of deposits in northern Central America, which is underlain by a pre-Mesozoic craton, ranged to higher 206Pb/204Pb and 207Pb/204Pb compositions than did deposits from elsewhere in the region, where the basement is Mesozoic oceanic material. Using 16 analyses for 12 new deposits, as well as new analyses for 11 of the samples studied previously, we have found that lead isotopic compositions correlate closely with crustal type but show little or no correlation with depth to the M-discontinuity. The deposits are divisible into three main groups including (in order of increasing 207Pb/204Pb and 208Pb/204Pb ratio): (1) deposits in southern Central America and all deposits in the Greater Antilles except Cuba; (2) all deposits in northern Central America; and (3) the Cuban deposits. Southern Central American and Caribbean lead is higher in 207Pb/204Pb and 208Pb/204Pb than most mid-ocean ridge basalts but could have been derived directly or indirectly from undepleted mantle. Northern Central America can be divided into the Maya block, which belongs to the Americas plate, and the Chortis block, which belongs to the Caribbean plate. Maya block deposits fall along a linear array whereas those of the Chortis block (except the Monte Cristo deposit) form a cluster. These results suggest that the Maya block is underlain by crust or mantle with a large range of U/Pb and Th/U ratios, whereas the Chortis block basement is more homogeneous. Two-stage model calculations indicate an age of about 2280+/-310 m.y. for the Maya block basement, although no such rocks are known in the region. Comparison of the Chortis block data to our recently published lead isotopic analyses of Mexican deposits shows considerable similarities suggesting that the Chortis block could have been derived from Mexico.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24169/1/0000428.pd

Magnetic Brightening of Carbon Nanotube Photoluminescence through Symmetry Breaking

Often a modification of microscopic symmetry in a system can result in a dramatic change in its macroscopic properties. Here we report that symmetry breaking by a tube-threading magnetic field can drastically increase the photoluminescence quantum yield of semiconducting single-walled carbon nanotubes, by as much as a factor of six, at low temperatures. To explain this striking connection between seemingly unrelated properties, we have developed a comprehensive theoretical model based on magnetic-field-dependent one-dimensional exciton band structure and the interplay of strong Coulomb interactions and the Aharonov-Bohm effect. This conclusively explains our data as the first experimental observation of dark excitons 5-10 meV below the bright excitons in single-walled carbon nanotubes. We predict that this quantum yield increase can be made much larger in disorder-free samples

Search for new phenomena in dijet events using 37 fb−1 of pp collision data collected at √s=13 TeV with the ATLAS detector

Dijet events are studied in the proton-proton collision data set recorded at s=13 TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to integrated luminosities of 3.5 fb-1 and 33.5 fb-1 respectively. Invariant mass and angular distributions are compared to background predictions and no significant deviation is observed. For resonance searches, a new method for fitting the background component of the invariant mass distribution is employed. The data set is then used to set upper limits at a 95% confidence level on a range of new physics scenarios. Excited quarks with masses below 6.0 TeV are excluded, and limits are set on quantum black holes, heavy W′ bosons, W∗ bosons, and a range of masses and couplings in a Z′ dark matter mediator model. Model-independent limits on signals with a Gaussian shape are also set, using a new approach allowing factorization of physics and detector effects. From the angular distributions, a scale of new physics in contact interaction models is excluded for scenarios with either constructive or destructive interference. These results represent a substantial improvement over those obtained previously with lower integrated luminosity