Relativistic Charged Balls

It is proven that the relativistic charged ball with its charge less than its mass (in natural units) cannot have a non-singular static configuration while its radius approaches its external horizon size. This conclusion does not depend on the details of charge distribution and the equation of state. The involved assumptions are (1) the ball is made of perfect fluid, (2) the energy density is everywhere non-negative.Comment: revtex, 11 page

Enhanced stability of superparamagnetic iron oxide nanoparticles in biological media using a pH adjusted-BSA adsorption protocol

Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used for biological applications due to their unique properties compared to their bulk counterparts, simplified SPIONs stabilization protocols applicable for a wide spectra of biological media remains a challenging issue. In this work, SPIONs with different surface coatings, tetramethylammonium hydroxide-coated SPIONs (T-SPIONs), and citrate-coated SPIONs (C-SPIONs) were synthesized by a facile, rapid and cost effective microwave-assisted method. C-SPIONs show robust stability in biological media of phosphate buffered saline and Roswell Park Memorial Institute Medium, while destabilize in DMEM. T-SPIONs were found to aggregate rapidly and significantly in all tested media. Then, a modified pH adjusted-BSA adsorption protocol and an addition of excess trisodium citrate dihydrate (Na3Cit) were used to enhance their stability in the media. The BSA adsorption protocol showed great efficiency in stabilizing the dispersed state of both SPIONs in the tested media, while the addition of excess Na3Cit showed limited effect, and it was only applicable for C-SPIONs. The formed BSA layer on SPIONs could be imaged by negative staining TEM, and revealed by Cryo-TEM, FTIR, DLS, and the zeta potential measurements. Results indicated that BSA forms a monolayer of a thickness of about 3 ± 1 nm and BSA interacts with C-SPIONs and T-SPIONs through their coating, rather than by replacing them. This synthetic method and stabilization protocol offer a general methodology to obtain SPIONs with a variety of surfactants, stable in different biological media in few minutes. © 2014 Springer Science+Business Media.Acknowledgments The research leading to these results has received funding from the People Program (Marie Curie Actions) of the European Union’s Seventh Framework Program (FP7/2007-2013) under REA grant agreement n8 303630 and cofounded by the European Social Fund. Authors acknowledge the funding from Spanish Ministry of Economy MAT 2012-35324, COST Action MP1202 and Ramon y Cajal grant RYC-2010-06082 (AL), China Scholarship Council fellowship (SMY, 201206150053).Peer Reviewe

Sequence entropy tuples and mean sensitive tuples

Using the idea of local entropy theory, we characterize the sequence entropy tuple via mean forms of the sensitive tuple in both topological and measure-theoretical senses. For the measure-theoretical sense, we show that for an ergodic measure-preserving system, the $\mu$-sequence entropy tuple, the $\mu$-mean sensitive tuple and the $\mu$-sensitive in the mean tuple coincide, and give an example to show that the ergodicity condition is necessary. For the topological sense, we show that for a certain class of minimal systems, the mean sensitive tuple is the sequence entropy tuple

Relativistic Charged Spheres II: Regularity and Stability

We present new results concerning the existence of static, electrically charged, perfect fluid spheres that have a regular interior and are arbitrarily close to a maximally charged black-hole state. These configurations are described by exact solutions of Einstein's field equations. A family of these solutions had already be found (de Felice et al., 1995) but here we generalize that result to cases with different charge distribution within the spheres and show, in an appropriate parameter space, that the set of such physically reasonable solutions has a non zero measure. We also perform a perturbation analysis and identify the solutions which are stable against adiabatic radial perturbations. We then suggest that the stable configurations can be considered as classic models of charged particles. Finally our results are used to show that a conjecture of Kristiansson et al. (1998) is incorrect.Comment: revtex, 13 pages. five EPS figures. Accepted by CQ

The predictive value of neutrophil-to-lymphocyte ratio for overall survival and pathological complete response in breast cancer patients receiving neoadjuvant chemotherapy

PurposePrevious studies have reported that neutrophil-to-lymphocyte ratio (NLR) at pre-treatment was predictive for overall survival (OS) and pathologic complete response (pCR) in breast cancer (BC) patients receiving neoadjuvant chemotherapy (NAC). This study aims to explore the predictive role of both pre- and post-NLR for OS as well as longitudinal NLR kinetics towards pCR in BC patients undergoing NAC.MethodsWe retrospectively included 501 BC patients who received NAC from 2009 to 2018. NLR at pre-, mid (every two cycles of NAC)-, and post-treatment were collected. Overall, 421 patients were included in the survival analysis. These patients were randomly divided into a training cohort (n = 224) and a validation cohort (n = 197). A multivariable Cox model was built using all significant factors in the multivariable analysis from the training cohort. The performance of the model was verified in the validation cohort by the concordance index (C-index). Longitudinal analysis for pCR prediction of NLR was performed using a mixed-effects regression model among 176 patients who finished eight cycles of NAC.ResultsThe median follow-up time was 43.2 months for 421 patients. In the training cohort, multivariable analysis revealed that ER status, clinical node stage, pCR, pre-NLR, and post-NLR (all p < 0.05) were independent predictors of OS. The OS nomogram was established based on these parameters. The C-indexes of the nomogram were 0.764 and 0.605 in the training and validation cohorts, respectively. In the longitudinal analysis, patients who failed to achieve pCR experienced an augment of NLR during NAC while NLR remained stable among patients with pCR. Pre-NLR tended to be significantly associated with OS in patients of HER2 overexpressing and TNBC subtypes (all p < 0.05), but not in Luminal A and Luminal B subtypes.ConclusionsThis study demonstrated the prognostic value of both pre-NLR and post-NLR on clinical outcomes in BC patients receiving NAC. A novel nomogram was established to predict OS. Non-pCR patients developed increased NLRs during NAC. Routine assessment of NLR may be a simple and affordable tool to predict prognosis for BC patients receiving NAC

On the temporal modelling of solar photovoltaic soiling: energy and economic impacts in seven cities

This work developed a framework to predict the energy and economic impacts of solar photovoltaic soiling. This framework includes the effects of relative humidity, precipitation and tilt angle on solar photovoltaic soiling. A concept of relative net-present value change was introduced to determine the optimal cleaning interval. The uncertainties in the economic analysis were accounted for using a Monte Carlo simulation method. The framework was used to study the soiling-induced efficiency and economic losses of solar photovoltaic modules in seven cities (i.e. Taichung, Tokyo, Hami, Malibu, Sanlucar la Mayor, Doha, and Walkaway). Overall, the efficiency loss (in ascending order) for Tokyo/Walkaway < Taichung < Sanlucar la Mayor < Malibu/Hami < Doha for a one-year study period. Doha experiences an efficiency loss over 80% for a 140-day exposure, while Tokyo has an efficiency loss less than 4% for a one-year exposure. Malibu has longest optimal cleaning intervals (70 days for manual cleaning and 49 days for machine-assisted cleaning) that leads to the relative net-present value changes of 1.7% and 1.1%. Doha has the shortest optimal cleaning intervals (23 days for manual cleaning and 17 days for machine-assisted cleaning) that leads to the relative net-present value changes of 21% and 19%. The work serves as an effective tool for designing optimal cleaning protocols for solar photovoltaic systems

Discovery of a spatially extended GeV source in the vicinity of the TeV halo candidate 2HWC J1912+099: a TeV halo or supernova remnant ?

Observations by HAWC and Milagro have detected spatially extended TeV sources surrounding middle-aged ($t\sim100-400 \,{\rm kyr}$) pulsars like Geminga and PSR B0656+14, which have been named "TeV Halos", representing very extended TeV pulsar wind nebulae (PWNe) powered by relatively old pulsars. A few more HAWC-detected sources have been suggested to be TeV halo candidates. In this paper, we search for possible GeV counterparts of three TeV halo candidates with Fermi Large Area Telescopes. We detect a new spatially extended GeV source in the vicinity of the TeV halo candidate 2HWC J1912+099, which is also detected by HESS (HESS J1912+101). We find that the size of the GeV source is significantly larger than that of the TeV emission measured by HESS, and a spatial template characteristic of a PWN can fit the GeV data. We suggest that the GeV source is an extended PWN powered by the central middle-aged pulsar PSR J1913+1011. This discovery favors the TeV halo scenario for the TeV source 2HWC J1912+099 (HESS J1912+101), although the possible shell-like morphology measured by HESS challenges this interpretation. Alternatively, the TeV emission could be dominated by a supernova remnant (SNR) via the hadronic process. Future multi-wavelength observations of the source and more precise measurements of the spatial profile of the TeV emission will be useful to distinguish between the two scenarios.Comment: Accepted by ApJ, 7 pages, 6 figure

Protective Effects of Bovine Serum Albumin on Superparamagnetic Iron Oxide Nanoparticles Evaluated in the Nematode Caenorhabditis elegans

Nanomaterials give rise to unique biological reactivity that needs to be thoroughly investigated. The quest for enhanced magnetic nanomaterials of different shapes, magnetic properties, or surface coatings continues for applications in drug delivery, targeting therapies, biosensing, and magnetic separation. In this context, the use of simple in vivo models, such as Caenorhabditis elegans, to biologically evaluate nanoparticles is currently in increasing demand as it offers low-cost and information-rich experiments. In this work, we evaluated how surface modification (citrate- and protein-coated) of superparamagnetic iron oxide nanoparticles (C-SPIONs and BSA-SPIONs, respectively) induces changes in their toxicological profile and biodistribution using the animal model C. elegans and combining techniques from materials science and biochemistry. The acute toxicity and nanoparticle distribution were assessed in two populations of worms (adults and larvae) treated with both types of SPIONs. After 24 h treatment, nanoparticles were localized in the alimentary system of C. elegans; acute toxicity was stronger in adults and larvae exposed to C-SPIONs rather than BSA-SPIONs. Adult uptake was similar for both SPION types, whereas uptake in larvae was dependent on the surface coating, being higher for BSA-SPIONs. Nanoparticle size was evaluated upon excretion, and a slight size decrease was found. Interestingly, all results indicate the protective effects of the BSA to prevent degradation of the nanoparticles and decrease acute toxicity to the worms, especially at high concentrations. We argue that this relevant information on the chemistry and toxicity of SPIONs in vivo could not be gathered using more classical in vitro approaches such as cell culture assays, thus endorsing the potential of C. elegans to assess nanomaterials at early stages of their synthetic formulations.C. elegans N2 and E. coli OP50 were provided by the CGC, which is funded by NIH Office of Research Infrastructure Programs (P40 OD010440). The research leading to these results has received funding from the People Program (Marie Curie Actions) of the European Union’s Seventh Framework Program (FP7/2007-2013) under REA grant agreement nº 303630 and cofounded by the European Social Fund. Authors acknowledge the funding from Spanish Ministry of Economy MAT 2012-35324 and FEDER funds, the Generalitat de Catalunya 2014SGR213, the COST Action MP1202, Ramon y Cajal grant RYC-2010-06082 (AL), China Scholarship Council fellowship (SMY, 201206150053), and FPU fellowship FPU12/05549 (LGM).Peer Reviewe