We develop a proper nonempirical spin-density formalism for the van der Waals density functional (vdW-DF) method. We show that this generalization, termed svdW-DF, is firmly rooted in the ...single-particle nature of exchange and we test it on a range of spin systems. We investigate in detail the role of spin in the nonlocal correlation driven adsorption of H_{2} and CO_{2} in the linear magnets Mn-MOF74, Fe-MOF74, Co-MOF74, and Ni-MOF74. In all cases, we find that spin plays a significant role during the adsorption process despite the general weakness of the molecular-magnetic responses. The case of CO_{2} adsorption in Ni-MOF74 is particularly interesting, as the inclusion of spin effects results in an increased attraction, opposite to what the diamagnetic nature of CO_{2} would suggest. We explain this counterintuitive result, tracking the behavior to a coincidental hybridization of the O p states with the Ni d states in the down-spin channel. More generally, by providing insight on nonlocal correlation in concert with spin effects, our nonempirical svdW-DF method opens the door for a deeper understanding of weak nonlocal magnetic interactions.
The Kuiper belt is a collection of small bodies (Kuiper belt objects, KBOs) that lie beyond the orbit of Neptune and which are believed to have formed contemporaneously with the planets. Their small ...size and great distance make them difficult to study. KBO 55636 (2002 TX300) is a member of the water-ice-rich Haumea KBO collisional family. The Haumea family are among the most highly reflective objects in the Solar System. Dynamical calculations indicate that the collision that created KBO 55636 occurred at least 1 Gyr ago. Here we report observations of a multi-chord stellar occultation by KBO 55636, which occurred on 9 October 2009 ut. We find that it has a mean radius of 143 ± 5 km (assuming a circular solution). Allowing for possible elliptical shapes, we find a geometric albedo of in the V photometric band, which establishes that KBO 55636 is smaller than previously thought and that, like its parent body, it is highly reflective. The dynamical age implies either that KBO 55636 has an active resurfacing mechanism, or that fresh water-ice in the outer Solar System can persist for gigayear timescales.
Primary outcome was to evaluate complete improvement at six months after acute treatment in NMOSD relapses.
Retrospective observational cohort study of patients with diagnosis of NMOSD admitted for ...acute attacks. We performed an explanatory analysis using the univariate, bivariate and multivariate logistic regression approach. We compared survival curves using the Kaplan Meier analysis and estimated the median time for the main outcome.
In the univariate analysis, basal EDSS score, AQP4-IgG positivity, PLEX as a first-line treatment (IVMP + PLEX), less systemic complications related to acute treatment and total attack history were independently associated with complete improvement at six months. After adjusting for confounding variables and using multivariate analysis by Cox Regression, positive AQ4-IgG (HR 0.04, 95% CI: 0.02–0.66) and IVMP + PLEX (HR 5.1, 95% CI: 3.9–66.4), were kept as independent factors associated to time to complete improvement. Time from admission to PLEX initiation and complete improvement at six months had a median of seven days (95% CI: 5.2–8.8). In secondary effects, there were no statistical differences between the groups.
PLEX + IVMP is the treatment of choice for NMOSD relapses and should be initiated as early as possible.
Devic's syndrome; Autoimmune diseases; Transverse myelitis; Optic neuritis; All Demyelinating disease (CNS).
ABSTRACT
The centaur (2060) Chiron exhibits outgassing behaviour and possibly hosts a ring system. On 2011 November 29, Chiron occulted a fairly bright star (R ∼ 15 mag) as observed from the 3-m NASA ...Infrared Telescope Facility (IRTF) on Mauna Kea and the 2-m Faulkes Telescope North (FTN) at Haleakala. Data were taken as visible wavelength images and simultaneous, low-resolution, near-infrared (NIR) spectra. Here, we present a detailed examination of the light-curve features in the optical data and an analysis of the NIR spectra. We place a lower limit on the spherical diameter of Chiron's nucleus of 160.2 ± 1.3 km. Sharp, narrow dips were observed between 280 and 360 km from the centre (depending on event geometry). For a central chord and assumed ring plane, the separated features are 298.5–302 and 308–310.5 km from the nucleus, with normal optical depth ∼0.5–0.9, and a gap of 9.1 ± 1.3 km. These features are similar in equivalent depth to Chariklo's inner ring. The absence of absorbing/scattering material near the nucleus suggests that these sharp dips are more likely to be planar rings than a shell of material. The region of relatively increased transmission is within the 1:2 spin-orbit resonance, consistent with the proposed clearing pattern for a non-axisymmetric nucleus. Characteristics of possible azimuthally incomplete features are presented, which could be transient, as well as a possible shell from ∼900–1500 km: future observations are needed for confirmation. There are no significant features in the NIR light curves, nor any correlation between optical features and NIR spectral slope.
Abstract
The physical response and geotechnical properties of diatomaceous soils are not fully understood, data are sparse, and do not account for the effects of single and multispecies frustule ...content, origin, type, and variability. The main physical problem lies in the irregular response of diatomaceous soils due to micro and nano scale causes and its unexpected effects on the macro scale. This research compared the characteristics of a multispecies diatomaceous soil sample (North American origin) with other diatomaceous single-species soils. Six artificial soil mixtures were prepared, dosed by weight, in order to determine the influence of the content of frustules. The results show that the liquid limit of the samples is lower than that of the monospecies samples for any content of frustules. The pore areas of the monospecies samples are found to be 4 to 7 times larger than those of the North American soil. Void ratios and compressibility ranges are higher as the diatom content increases. The internal friction angle of diatomaceous soils varies in a non-linear tendency with respect to fossil content. For the studied soil at 100% fossil concentration, the internal friction angle reached 38.32°, a magnitude that is lower than the values reported for most of the monospecies contrast samples.
•Analysis of Pluto occultation data from 2012 to 2013.•Pluto’s atmosphere persists and will likely do so through 2015.•Discussion of the difference between shadow radius and pressure at a level in ...the atmosphere.
We observed two stellar occultations on UT 4 May 2013 and UT 9 September 2012, with the aim of measuring Pluto’s atmospheric parameters. Both of these events were observed by world-wide collaborations of many observers, and both occurred within 1month of Pluto’s stationary points. The PC20120909 event was observed at the McDonald Observatory (MONET 1.2-m), and Olin Observatory (the Ortega 0.8-m); the P20130504 event was observed at the Las Campanas Observatory (du Pont 2.5-m), the Cerro Tololo Inter-American Observatory (SMARTS 1-m), and the Cerro Calán National Astronomical Observatory (Goto 0.45-m). Analysis of the data indicates an atmospheric state similar to that in June 2011. The shadow radius for the event is unchanged from recent events, indicating an atmosphere that is holding stable and not in the midst of global collapse. We discuss the advantages and disadvantages of comparing various atmospheric parameters across events (the shadow radius vs. the pressure at a particular radius). These analyses suggest that Pluto will still have an atmosphere when the New Horizons spacecraft arrives in July 2015.
•We present an analysis of a double stellar occultation observation, by Pluto and Charon.•Multiwavelength data are consistent with haze in Pluto’s lower atmosphere in 2011.•The best-fit, simple, haze ...model contains spherical, micron-sized tholins.
Pluto’s lower atmosphere has been observed to evolve since the first definitive occultation detection in 1988. Possibilities for explaining the lower atmospheric structure include a steep thermal gradient and/or extinction, the latter of which can be characterized as a dependence between occultation flux and wavelength. On 2011 June 23, a 14.43 UCAC magnitude star (R=13.64) was occulted by Pluto as observed from multiple sites. Observations made at NASA’s 3-m Infrared Telescope Facility (IRTF) on Mauna Kea, Hawai’i, showed a full occultation of the star by Charon followed by an atmospheric graze by Pluto. Data were taken simultaneously in visible-wavelength images and low-resolution, near-infrared spectra. This dataset is unique in that (i) the double occultation allows astrometric measurements for Pluto and Charon as well as accurate calibration of the Pluto light curve, and (ii) the wavelength-resolved data serve as a test for atmospheric extinction. The graze reached a minimum normalized flux level of roughly 0.35, serving primarily as a probe of Pluto’s upper atmosphere (which is typically defined to be above half-light level in occultation light curves). However, the light curve is well fit by atmospheric models with a power-law thermal gradient, a clear upper atmosphere, and haze in the lower atmosphere. We find a negative dependence between flux and wavelength in the deepest part of Pluto’s atmosphere probed by the graze and in a spike during emersion. A simple extinction model for spherical, μm-sized tholins matches the observed spectral trends. While the atmospheric fits cannot rule out a clear atmosphere having a steep thermal gradient at the bottom, the flux-wavelength dependence and the feasibility of our particle-scattering fits suggest that Pluto’s lower atmosphere contained haze in 2011. These results provide an important link in monitoring Pluto’s dynamic atmosphere.
In this work we model and simulate water quality parameters in a hydrological network by using a methodology based on network theory and differential equations. We build the Quindío river ...hydrological network based on network theory using the Gephi software, the maps from "Instituto Geográfico de Colombia Agustin Codazzi" and data reported from "Coorporacion Autónoma Regional del Quindío". Then, we modelled three water quality parameters using differential equations at each node of the network, these are total coliforms, biochemical oxygen demand, and dissolved oxygen. As a result of the simulations, we found high levels of pollution in the area where there is a presence of human settlements and the local industry. Finally, results also showed a possible relationship between the three parameters studied, mainly due to the high concentrations in the same area of the basin.
Background
Microplastics (MPs) and nanoplastics (NPs) have become a growing concern in dermatology due to their widespread presence in cosmetic formulations and the environment. These minuscule ...synthetic polymer particles prompt an essential exploration of their potential impact on dermatological homeostasis.
Aims
This study aims to investigate the effects of MPs and NPs on the integumentary system. Specifically, it seeks to understand the potential cutaneous alterations, inflammatory responses, and disruptions to the skin's physiological functions caused by these synthetic particles.
Patients/Methods
The investigation involves a comprehensive analysis of emerging research on MPs and NPs. This includes their presence in cosmetic formulations and environmental pervasiveness. The study delves into their capacity to breach the cutaneous barrier, raising concerns about the implications of prolonged exposure.
Results
Evidence suggests that MPs and NPs may indeed incite cutaneous alterations, provoke inflammatory responses, and disturb the homeostasis of the skin's physiological functions. Their small dimensions enhance their capability to breach the cutaneous barrier, further emphasizing the apprehensions associated with prolonged exposure.
Conclusions
While a precise understanding of the implications of MPs and NPs on dermatological health remains an ongoing scientific endeavor, this study underscores the growing significance of these synthetic particles. The findings emphasize the need for proactive measures to safeguard both individual well‐being and environmental preservation in the context of dermatological health.
The core of the Santander Massif in the northern Andes of Colombia is dominated by migmatitic gneisses with a <1.71Ga protolith and was affected by continuous interactions of oceanic plates to the ...west and the northwestern corner of the South American continental plate. The exposed metamorphic core of the massif offers a unique opportunity to understand the tectonic evolution of northwestern South America. We present new metamorphic petrology and geochemistry data from the Bucaramanga Gneiss in the Santander Massif to document part of this tectonic evolution from late Proterozoic to Jurassic times.
Metapelitic migmatite gneiss, quartz-feldspathic gneiss, and amphibolite from the Bucaramanga Gneiss recorded metamorphic peak conditions in the range of 660–850°C at pressures of >7.5kbar. Lithologies are overprinted by low-pressure metamorphism, related to extensive Jurassic intrusions and linked with growth of cordierite and equilibration of low-pressure mineral assemblages, recorded metamorphic conditions are <750°C and <6.5kbar.
Observed leucosomes display significant compositional variations and can be grouped in three groups: i) Group One leucosomes with high total REE content, high LREE/HREE, and negative Eu anomaly, ii) Group Two leucosomes with low total REE, low LREE/HREE, and positive Eu anomalies, and iii) Group Three leucosomes with relatively low LREE/HREE and strong positive Eu anomaly. Geochemical data support the interpretation that Group Two leucosomes crystallized from melts originated in a partial melting event affecting mostly pelitic and quartz-feldspathic lithologies with fluid-present melting reactions. The evaluation of mesosomes (amphibolite, pelitic and quartz-feldspathic rocks) as potential protoliths or restites indicates that at least two pelitic samples of the analyzed lithologies have characteristics consistent with the occurrence of fluid-present melting reactions involving quartz and feldspar. The leucosomes produced by crystallization of modified partial melts contrast with several other leucosomes that were injected; however, in some cases the melts crystallized as injected leucosomes show consistent geochemistry with partial melting of lithologies geochemically similar to the ones observed in the unit.
The migmatization and the low pressure metamorphic overprint are related here to two main tectonic events: an early Paleozoic tectonic pulse produced by subduction of the oceanic crust of the Iapetus Ocean beneath northwestern Gondwana, and an Upper Triassic to Lower Jurassic tectonic pulse produced by subduction of oceanic crust of the proto-Pacific ocean beneath western Pangaea.
•The migmatitic Bucaramanga Gneiss reached the granulite facies conditions at temperatures up to 800ºC.•Local partial melts likely formed by fluid-present melting of pelites and quartz-feldspathic rocks.•A subsequent low-pressure metamorphic event overprinted the migmatites, this tectonic episode produced growth of cordierite.•Low-pressure metamorphic event is interpreted to be related to a low lying Jurassic magmatic arc in South America.
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