352 research outputs found

    The Twist of the Draped Interstellar Magnetic Field Ahead of the Heliopause: A Magnetic Reconnection Driven Rotational Discontinuity

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    Based on the difference between the orientation of the interstellar BISMB_{ISM} and the solar magnetic fields, there was an expectation that the magnetic field direction would rotate dramatically across the heliopause (HP). However, the Voyager 1 spacecraft measured very little rotation across the HP. Previously we showed that the BISMB_{ISM} twists as it approaches the HP and acquires a strong T component (East-West). Here we establish that reconnection in the eastern flank of the heliosphere is responsible for the twist. On the eastern flank the solar magnetic field has twisted into the positive N direction and reconnects with the Southward pointing component of the BISMB_{ISM}. Reconnection drives a rotational discontinuity (RD) that twists the BISMB_{ISM} into the -T direction and propagates upstream in the interstellar medium towards the nose. The consequence is that the N component of BISMB_{ISM} is reduced in a finite width band upstream of the HP. Voyager 1 currently measures angles (δ=sin1(BN/B)\delta=sin^{-1}(B_{N}/B)) close to solar values. We present MHD simulations to support this scenario, suppressing reconnection in the nose region while allowing it in the flanks, consistent with recent ideas about reconnection suppression from diamagnetic drifts. The jump in plasma β\beta (the plasma to magnetic pressure) across the nose of HP is much greater than in the flanks because the heliosheath β\beta is greater there than in the flanks. Large-scale reconnection is therefore suppressed in the nose but not at the flanks. Simulation data suggest that BISMB_{ISM} will return to its pristine value 1015 AU10-15~AU past the HP.Comment: 19 pages, 5 figures, submitte

    Restoration of Sensitivity in Chemo

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    Glioblastoma (GBM) is the most common and aggressive brain tumor in adults. Despite multimodal treatments including surgery, chemotherapy and radiotherapy the prognosis remains poor and relapse occurs regularly. The alkylating agent temozolomide (TMZ) has been shown to improve the overall survival in patients with malignant gliomas, especially in tumors with methylated promoter of the O6-methylguanine-DNA-methyltransferase (MGMT) gene. However, intrinsic and acquired resistance towards TMZ makes it crucial to find new therapeutic strategies aimed at improving the prognosis of patients suffering from malignant gliomas. Cold atmospheric plasma is a new auspicious candidate in cancer treatment. In the present study we demonstrate the anti-cancer properties of different dosages of cold atmospheric plasma (CAP) both in TMZ-sensitive and TMZ-resistant cells by proliferation assay, immunoblotting, cell cycle analysis, and clonogenicity assay. Importantly, CAP treatment restored the responsiveness of resistant glioma cells towards TMZ therapy. Concomitant treatment with CAP and TMZ led to inhibition of cell growth and cell cycle arrest, thus CAP might be a promising candidate for combination therapy especially for patients suffering from GBMs showing an unfavorable MGMT status and TMZ resistance

    Consistent Calculation of the Nucleon Electromagnetic Polarizabilities in Chiral Perturbation Theory Beyond Next-to-Leading Order

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    We calculate the nucleons' electromagnetic polarizabilities in heavy baryon chiral perturbation theory including all terms to order O(q4){\cal O} (q^4). The chiral prediction of the electric polarizabilities for the neutron and the proton are in good agreement with the data. In the case of the magnetic polarizabilities the big positive contribution from the Δ(1232)\Delta(1232) resonance is largely cancelled by a non--analytic loop contribution of the lnMπ\ln M_\pi type. This novel effect helps to understand the rather small empirical value of the nucleons' magnetic polarizability.Comment: 10 pp, TeX, BUTP-93/22 and CRN-93-3

    Comprehensive Analyses of Coagulation Parameters in Patients with Vascular Anomalies.

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    BACKGROUND Vascular anomalies comprise a diverse group of rare diseases with altered blood flow and are often associated with coagulation disorders. The most common example is a localized intravascular coagulopathy in venous malformations leading to elevated D-dimers. In severe cases, this may progress to a disseminated intravascular coagulopathy with subsequent consumption of fibrinogen and thrombocytes predisposing to serious bleeding. A separate coagulopathy is the Kasabach-Merritt phenomenon in kaposiform hemangioendothelioma characterized by platelet trapping leading to thrombocytopenia and eventually consumptive coagulopathy. Our previous work showed impaired von Willebrand factor and platelet aggregometry due to abnormal blood flow, i.e., in ventricular assist devices or extracorporeal membrane oxygenation. With altered blood flow also present in vascular anomalies, we hypothesized that, in particular, the von Willebrand factor parameters and the platelet function may be similarly impacted. METHODS We prospectively recruited 73 patients with different vascular anomaly entities and analyzed their coagulation parameters. RESULTS Acquired von Willebrand syndrome was observed in both of our patients with Kasabach-Merritt phenomenon. In six out of nine patients with complex lymphatic anomalies, both the vWF antigen and activity were upregulated. Platelet aggregometry was impaired in both patients with Kasabach-Merritt phenomenon and in seven out of eight patients with an arteriovenous malformation. CONCLUSIONS The analysis of coagulation parameters in our patients with vascular anomalies advanced our understanding of the underlying pathophysiologies of the observed coagulopathies. This may lead to new treatment options for the, in part, life-threatening bleeding risks in these patients in the future

    Optimizing Combination of Parameters for Pull-off Adhesion Testing through Design of Experiment Study

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    A minimum of adhesion strength of thin films and coatings to substrates is required for their durable applications. Practical Adhesion is measure of that strength required to pull-off coating or film from the substrate. A suitable method to measure this adhesion strength has to be one that allows quantitative repeatable hence reliable results. There are many methods and techniques to measure this practical adhesion. However, none inclusively quantifies adhesion with repeatable results. Pull-Off method involves application of tensile forces and delivers quantitative results. Here we report optimizations made in combination of parameters for Pull-Off adhesion testing. Optimized combination of adhesive mixing ratio, time for hardening (curing), time to test after hardening and applied force rate was achieved through detailed Design of Experiment study. Achieved combination delivered results which were quantitative, repeatable, consistent and uniform and allowed application of method to a variety of coatings and films with enhanced reliability. The improvements here in reported are applicable to majority of thin films and coating systems delivering some standardized parameters combination for pull-off method

    Effect of hygroscopic growth on the aerosol light-scattering coefficient: A review of measurements, techniques and error sources

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    Knowledge of the scattering enhancement factor, f(RH), is important for an accurate description of direct aerosol radiative forcing. This factor is defined as the ratio between the scattering coefficient at enhanced relative humidity, RH, to a reference (dry) scattering coefficient. Here, we review the different experimental designs used to measure the scattering coefficient at dry and humidified conditions as well as the procedures followed to analyze the measurements. Several empirical parameterizations for the relationship between f(RH) and RH have been proposed in the literature. These parameterizations have been reviewed and tested using experimental data representative of different hygroscopic growth behavior and a new parameterization is presented. The potential sources of error in f(RH) are discussed. A Monte Carlo method is used to investigate the overall measurement uncertainty, which is found to be around 20 e40% for moderately hygroscopic aerosols. The main factors contributing to this uncertainty are the uncertainty in RH measurement, the dry reference state and the nephelometer uncertainty. A literature survey of nephelometry-based f(RH) measurements is presented as a function of aerosol type. In general, the highest f(RH) values were measured in clean marine environments, with pollution having a major influence on f(RH). Dust aerosol tended to have the lowest reported hygroscopicity of any of the aerosol types studied. Major open questions and suggestions for future research priorities are outlined.This work was supported by the Andalusia Regional Government through projects P10-RNM-6299 and P12-RNM-2409; by the Spanish Ministry of Economy and Competitiveness and FEDER through project CGL2013_45410-R; and by European Union’s Horizon 2020 research and innovation programme under grant agreement No 654109, ACTRIS-2. G. Titos was partially funded by Programa del Plan Propio de Investigación “Contrato Puente” of the University of Granada. We thank the Stockholm International Meteorological Institute (IMI) for travel support of G. Titos

    Deeply Virtual Compton Scattering

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    We study in QCD the physics of deeply-virtual Compton scattering (DVCS)---the virtual Compton process in the large s and small t kinematic region. We show that DVCS can probe a new type of off-forward parton distributions. We derive an Altarelli-Parisi type of evolution equations for these distributions. We also derive their sum rules in terms of nucleon form-factors of the twist-two quark and gluon operators. In particular, we find that the second sum rule is related to fractions of the nucleon spin carried separately by quarks and gluons. We estimate the cross section for DVCS and compare it with the accompanying Bethe-Heitler process at CEBAF and HERMES kinematics.Comment: 20 pages, 2 figures, replaced with the version to appear in Phys. Rev.

    Probing IMF using nanodust measurements from inside Saturn's magnetosphere

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    We present a new concept of monitoring the interplanetary magnetic field (IMF) by using in situ measurements of nanodust stream particles in Saturn's magnetosphere. We show that the nanodust detection pattern obtained inside the magnetosphere resembles those observed in interplanetary space and is associated with the solar wind compression regions. Our dust dynamics model reproduces the observed nanodust dynamical properties as well as the detection pattern, suggesting that the ejected stream particles can reenter Saturn's magnetosphere at certain occasions due to the dynamical influence from the time‐varying IMF. This method provides information on the IMF direction and a rough estimation on the solar wind compression arrival time at Saturn. Such information can be useful for studies related to the solar wind‐magnetosphere interactions, especially when the solar wind parameters are not directly available. Key Points A new method to probe IMF with nanodust measurements inside the magnetosphere Under changing IMF, ejected nanoparticles can re‐enter Saturn‐s magnetosphere IMF direction and solar wind compression arrival time can be derivedPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99078/1/grl50604.pd
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