The nucleon spin and momentum decomposition using lattice QCD simulations

We determine within lattice QCD, the nucleon spin carried by valence and sea quarks, and gluons. The calculation is performed using an ensemble of gauge configurations with two degenerate light quarks with mass fixed to approximately reproduce the physical pion mass. We find that the total angular momentum carried by the quarks in the nucleon is $J_{u+d+s}{=}0.408(61)_{\rm stat.}(48)_{\rm syst.}$ and the gluon contribution is $J_g {=}0.133(11)_{\rm stat.}(14)_{\rm syst.}$ giving a total of $J_N{=}0.54(6)_{\rm stat.}(5)_{\rm syst.}$ consistent with the spin sum. For the quark intrinsic spin contribution we obtain $\frac{1}{2}\Delta \Sigma_{u+d+s}{=}0.201(17)_{\rm stat.}(5)_{\rm syst.}$. All quantities are given in the $\overline{\textrm{MS}}$ scheme at 2~GeV. The quark and gluon momentum fractions are also computed and add up to $\langle x\rangle_{u+d+s}+\langle x\rangle_g{=}0.804(121)_{\rm stat.}(95)_{\rm syst.}+0.267(12)_{\rm stat.}(10)_{\rm syst.}{=}1.07(12)_{\rm stat.}(10)_{\rm syst.}$ satisfying the momentum sum.Comment: Version published in PR

Level and length of cyclic solar activity during the Maunder minimum as deduced from the active day statistics

The Maunder minimum (MM) of greatly reduced solar activity took place in 1645-1715, but the exact level of sunspot activity is uncertain as based, to a large extent, on historical generic statements of the absence of spots on the Sun. Here we aim, using a conservative approach, to assess the level and length of solar cycle during the Maunder minimum, on the basis of direct historical records by astronomers of that time. A database of the active and inactive days (days with and without recorded sunspots on the solar disc respectively) is constructed for three models of different levels of conservatism (loose ML, optimum MO and strict MS models) regarding generic no-spot records. We have used the active day fraction to estimate the group sunspot number during the MM. A clear cyclic variability is found throughout the MM with peaks at around 1655--1657, 1675, 1684 and 1705, and possibly 1666, with the active day fraction not exceeding 0.2, 0.3 or 0.4 during the core MM, for the three models. Estimated sunspot numbers are found very low in accordance with a grand minimum of solar activity. We have found, for the core MM (1650-1700), that: (1) A large fraction of no-spot records, corresponding to the solar meridian observations, may be unreliable in the conventional database. (2) The active day fraction remained low (below 0.3-0.4) throughout the MM, indicating the low level of sunspot activity. (3) The solar cycle appears clearly during the core MM. (4) The length of the solar cycle during the core MM appears $9\pm 1$ years, but there is an uncertainty in that. (5) The magnitude of the sunspot cycle during MM is assessed to be below 5-10 in sunspot numbers; A hypothesis of the high solar cycles during the MM is not confirmed.Comment: Accepted to Astron. Astrophy

Nucleon scalar and tensor charges using lattice QCD simulations at the physical value of the pion mass

We present results on the light, strange and charm nucleon scalar and tensor charges from lattice QCD, using simulations with $N_f=2$ flavors of twisted mass Clover-improved fermions with a physical value of the pion mass. Both connected and disconnected contributions are included, enabling us to extract the isoscalar, strange and charm charges for the first time directly at the physical point. Furthermore, the renormalization is computed non-perturbatively for both isovector and isoscalar quantities. We investigate excited state effects by analyzing several sink-source time separations and by employing a set of methods to probe ground state dominance. Our final results for the scalar charges are $g_S^u = 5.20(42)(15)(12)$, $g_S^d = 4.27(26)(15)(12)$, $g_S^s=0.33(7)(1)(4)$, $g_S^c=0.062(13)(3)(5)$ and for the tensor charges $g_T^u = 0.782(16)(2)(13)$, $g_T^d = -0.219(10)(2)(13)$, $g_T^s=-0.00319(69)(2)(22)$, $g_T^c=-0.00263(269)(2)(37)$ in the $\overline{\rm MS}$ scheme at 2~GeV. The first error is statistical, the second is the systematic error due to the renormalization and the third the systematic arising from possible contamination due to the excited states.Comment: 20 pages and 13 figure

Exposure to graphene in a pilot production plant

Workers exposure to graphene was measured in a pilot production plant. Reduced graphene oxide was produced through graphite oxidation and posterior thermal reduction. The monitoring was performed using two handheld on-line devices covering the particle size range from 10 nm to 10 μm (CPC3007 and OPS3330). Simultaneously, personal and area filter samples were collected for off line analysis, including gravimetric, elemental carbon analysis and SEM/EDX. Significant releases of particles were identified in two tasks, during the graphene oxide washing, and during its milling. However, the analysis of the particles size distribution and of their morphology suggested that the released particles were not the target nanomaterial but engine generated nanoparticles. The mass of elemental carbon in the collected filters was below the quantification limit and the calculated graphene mass concentrations were quite below the selected reference exposure limit. Overall, this work showed that worker exposure to graphene was low in this pilot plant, contributing to guarantee a safe process, prior to its industrialization.This research was carried out as part of the project FAST- Functionally Graded Additive Manufacturing Scaffolds by Hybrid Manufacturing. The project FAST has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 685825

Traumatic brain injury: Failure of the intravenous route for the administration of bone marrow stromal stem cells as treatment of chronic neurological sequels

Objetivo: Estudiar el posible efecto terapéutico de la administración intravenosa de células madre estromales (CME) obtenidas de médula ósea para tratar las secuelas neurológicas en fase crónica tras una lesión cerebral traumática. Material y método: Se realizó un modelo de lesión cerebral traumática en ratas Wistar adultas y se estudió el déficit neurológico inducido en el curso de los dos meses siguientes, por medio del test mNSS y el test Smart. Tras ese tiempo, en fase de secuelas crónicamente establecidas, se administraron intravenosamente 15 x 106 CME (n:10) o suero fisiológico (n:10). En los dos meses siguientes se estudió la posible modificación de las secuelas neurológicas. Resultados: Cuando se compararon los resultados de la valoración funcional entre ambos grupos experimentales, no se observaron diferencias estadísticamente significativas. Conclusión: Nuestros resultados sugieren que el trasplante de CME por vía intravenosa, en una fase de secuelas crónicamente establecidas tras una lesión traumática cerebral grave, no tiene efecto terapéuticoObjective: We studied the possible therapeutic effect of intravenous administration (noninvasive method) of BMSCs to treat neurological sequels in a chronic stage after TBI. Material and method: A model of TBI in adult Wistar rats was performed and we studied the neurological deficit induced in the course of two months, through the mNSS and Smart tests. After this time, with established sequels, 15 x 106 BMSCs (n = 10) or saline (n = 10) were administered intravenously. Changes in the neurological deficits were studied in two months. Results: Comparison of functional changes between both experimental groups showed no statistically significant differences. Conclusions: Our results suggest that transplantation of BMSCs intravenously, at a stage of established sequels after severe TBI, has no therapeutic effectEsta investigación ha sido financiada por FUNDACIÓN MAPFR

Influence of the level of neurological deficit on the efficacy of cell therapy in a model of severe traumatic brain injury

Objetivo: Determinar si el nivel de déficit neurológico influye en la eficacia de la terapia celular con células madre mesenquimales (CMM) de la médula ósea en un modelo experimental crónico de lesión cerebral traumática. Material y métodos: Se sometió a ratas Wistar adultas a un modelo de lesión cerebral traumática. Dos meses después, se clasificaron en función de su nivel de déficit neurológico mediante dos tests funcionales: Escala de valoración sensitivo-motora y Tiempo de permanencia en la zona interior (Video-Tracking-Box test, VTB test). Se inyectó suero salino solo o CMM en suero salino en el tejido cerebral dañado de los animales que obtuvieron la clasificación neurológica de lesión moderada o grave según el nivel permanente de su déficit funcional. Todos los animales se evaluaron durante los dos meses siguientes para determinar la posible eficacia de la administración de las CMM. Al finalizar el estudio, los animales se eutanasiaron y se estudiaron sus cerebros. Resultados: Se constata una recuperación funcional significativa en los animales con lesión moderada que recibieron las CMM, pero no en los animales con lesión grave cuando se compara con los controles. Conclusiones: Las conclusiones obtenidas sugieren que la gravedad de la lesión neurológica puede influir en la potencial eficacia de la terapia celular cuando es aplicada en una lesión cerebral traumática crónicaObjective: To study if the level of neurological deficit influences the efficacy of cell therapy with bone marrow stromal cells (BMSC), in an experimental model of chronic traumatic brain injury (TBI). Material and methods: Adult Wistar rats were subjected to a model of traumatic brain injury. Two months later they were classified according to their level of neurological deficit. For that, two functional tests: Scale of sensory- motor assessment and time spent in the inner zone in the Video-Tracking-Box test, were used. Saline alone or BMSC in saline was injected into the damaged brain tissue of animals suffering a permanent level of functional deficit classified as moderate or severe. All experimental groups were evaluated during the next two months to determine the potential effectiveness of the intracerebral administration of BMSC. At the end of the study animals were euthanized and their brains were studied. Results: The results show a significant functional recovery in animals with moderate injury who received BMSC, but there was no significant recovery in animals with severe traumatic brain injury when compared with controls. Conclusion: The severity of neurologic injury may influence the potential efficacy of cell therapy applied to chronic TBIEsta investigación ha sido financiada por FUNDACIÓN MAPFR