Partial Cover Research Articles

CLASSY. X. Highlighting Differences between Partial Covering and Semianalytic Modeling in the Estimation of Galactic Outflow Properties

Feedback-driven massive outflows play a crucial role in galaxy evolution by regulating star formation and influencing the dynamics of surrounding media. Extracting outflow properties from spectral lines is a notoriously difficult process for a number of reasons, including the possibility that a substantial fraction of the outflow is carried by dense gas in a very narrow range in velocity. This gas can hide in spectra with insufficient resolution. Empirically motivated analysis based on the apparent optical depth method, commonly used in the literature, neglects the contribution of this gas, and may therefore underestimate the true gas column density. More complex semianalytical line transfer (e.g., SALT) models, on the other hand, allow for the presence of this gas by modeling the radial density and velocity of the outflows as power laws. Here we compare the two approaches to quantify the uncertainties in the inferences of outflow properties based on 1D “down-the-barrel” spectra, using the UV spectra of the CLASSY galaxy sample. We find that empirical modeling may significantly underestimate the column densities relative to SALT analysis, particularly in the optically thick regime. We use simulations to show that the main reason for this discrepancy is the presence of a large amount of dense material at low velocities, which can be hidden by the finite spectral resolution of the data. The SALT models in turn could overestimate the column densities if the assumed power laws of the density profiles are not a property of actual outflows.

The Cooperative Maximal Covering Location Problem with ordered partial attractions

The Maximal Covering Location Problem (MCLP) is a classical location problem where a company maximizes the demand covered by placing a given number of facilities, and each demand node is covered if the closest facility is within a predetermined radius. In the cooperative version of the problem (CMCLP), it is assumed that the facilities of the decision maker act cooperatively to increase the customers’ attraction towards the company. In this sense, a demand node is covered if the aggregated partial attractions (or partial coverings) of open facilities exceed a threshold. In this work, we generalize the CMCLP introducing an Ordered Median function (OMf), a function that assigns importance weights to the sorted partial attractions of each customer and then aggregates the weighted attractions to provide the total level of attraction. We name this problem the Ordered Cooperative Maximum Covering Location Problem (OCMCLP). The OMf serves as a means to compute the total attraction of each customer to the company as an aggregation of ordered partial attractions and constitutes a unifying framework for CMCLP models.We introduce a multiperiod stochastic non-linear formulation for the CMCLP with an embedded assignment problem characterizing the ordered cooperative covering. For this model, two exact solution approaches are presented: a MILP reformulation with valid inequalities and an effective approach based on Generalized Benders’ cuts. Extensive computational experiments are provided to test our results with randomly generated data and the problem is illustrated with a case study of locating charging stations for electric vehicles in the city of Trois-Rivières, Québec (Canada).

A Comprehensive Analysis of Reported Adverse Events and Device Failures Associated with Esophageal Self-Expandable Metal Stents: An FDA MAUDE Database Study.

Esophageal Stents are used to maintain esophageal lumen patency in esophageal strictures caused by intrinsic and/or extrinsic malignancies and the occlusion of concomitant esophageal fistulas. While data on the efficacy and safety of esophageal stents exist, comprehensive evaluation of adverse events is limited. The aim of this study is to investigate the reported adverse events and device failures associated with esophageal self-expandable metal stents (SEMS) using the FDA's Manufacturer and User Facility Device Experience (MAUDE) database. Post-marketing surveillance data for the esophageal SEMSs were analyzed using the FDA's MAUDE database from January 2014 to December 10, 2023. The outcomes of interest were patient-related adverse events and device failures. Statistical analysis was performed using Microsoft Excel 2010 and SPSS. Pooled numbers and percentages were calculated for each adverse event. Continuous variables underwent analysis using a two-tailed student t test, and significance was set to p ≤ 0.05. During the study period, 548 MAUDE reports revealed 873 device failures and 186 patient-related adverse events. The most common device issues were stent activation, positioning, or separation problems (4 n = 403; 46.2%), followed by device detachment or migration (n = 109, 12.5%), and material problems (n = 93, 10.7%). Patient complications included dysphagia/odynophagia (10%), perforation, pain, and bleeding (each 7.6%). The most common device failures in over-the-wire (OTW) stents and through-the-scope (TTS) stents were activation, positioning, or separation problems (TTS: n = 183, 52.6% vs OTW: n = 220, 41.9%). Compared to OTW stents, TTS stents had higher migration and breakage (13.5% vs. 11.8%, p = 0.24), and (9.2% vs. 6.7%, p = 0.08) respectively, while OTW stents had more challenges with stent advancement or removal (5.1% vs. 0.3%, p < 0.001 and 4.6% vs 3.4%, p = 0.19, respectively) and material problems (14.7% vs. 4.6%, p < 0.001). Activation, positioning, and separation problems were the most frequent device failures in fully covered (FC) and partially covered (PC) stents (FC: n = 62, 32.8%, PC: n = 168, 43.5%). FC stents had higher migration rates (20.6% vs 9.8%, p < 0.001), while PC stents exhibited more material problems (17.4% vs. 5.8%, p < 0.001) and difficulties with advancing the stents (6.7% vs. 0%, p < 0.001). Our examination showed a prevalence of reported device complications associated with stent activation, positioning, and separation problems. Dysphagia or odynophagia emerged as the most frequently reported patient complication. Furthermore, our analysis, provides insights into TTS vs. OTW and FC vs. PC esophageal SEMSs, enabling endoscopists and manufacturers to better understand adverse events and potentially optimize device design for future iterations.

Novel Bi-Functional MoS2/α-Fe2O3 Nanocomposites for High Photocatalytic Performance

In this study, 3-dimensional molybdenum disulfide (MoS2) structures, integrated with hematite (α-Fe2O3) nanoparticles, were fabricated under a convenient two-step hydrothermal route. The fabricated photocatalytic nanocomposites consist of well-arranged MoS2 flakes, resembling spherical flower-like morphology, and the nanoparticulate α-Fe2O3 structures decorate the 3D network. By raising the α-Fe2O3 weight ratio, the composites’ specific surface area and morphology were not affected, regardless of the partial cover of the cavities for higher hematite content. Moreover, the crystallinity examination with XRD, Raman, and FTIR techniques revealed that the precursor reagents were fully transformed to well-crystalized MoS2 and Fe2O3 composites of high purity, as no organic or inorganic residues could be detected. The photocatalytic oxidation and reduction performance of these composites was evaluated against the tetracycline pharmaceutical and the industrial pollutant hexavalent chromium, respectively. The improvement in the removal efficiencies demonstrates that the superior photoactivity originates from the high crystallinity and homogeneity of the composite, in combination with the enhanced charge carriers’ separation in the semiconductors’ interface.

Modeling and probabilistic evaluation of repair strategies in the initiation phase of chloride‐induced corrosion of the reinforcement of concrete structures

AbstractChloride ingress is a common issue in concrete structures that can result in reinforcement corrosion. In order to extend the lifetime of a structure, several preventive repair methodologies are available, which reduce the ingress of chlorides. In this work, the computational efficiency of the analytical model for a two‐material diffusion problem has been improved to model the effect of a mortar overlay or partial cover replacement, and is further implemented to model the influence of a coating. This enables the assessment of each repair method in a probabilistic framework using Latin hypercube samples within an acceptable timeframe. A parameter study executed in both a deterministic and probabilistic framework demonstrated the model efficiency and the importance of the timing and quality of the intervention for successful repair when applying a repair intervention in the initiation phase.

Influence of partial cover thickness and mortar quality on steel corrosion in a chloride environment

Influence of partial cover thickness and mortar quality on steel corrosion in a chloride environment

Effect of Silane and Silicate based Penetrants against Corrosion of Steel with Partial Cover Thickness

The partial cover thickness of reinforced concrete structures near the coastline enhances the early corrosion onset, which reduces the service life. As a countermeasure under the preventive maintenance approach, to delay early corrosion onset in structures with partial cover thickness and increase durability throughout the service life, this study used silane and silicate-based surface penetrants. Mortar specimens with a partial cover thickness and embedded, specially segmented bars were prepared. Both penetrants were applied to specimens with partial cover thicknesses (20 and 7.5 mm). Further, electrochemical methods such as macrocell current, microcell current, electric resistivity, and potentiodynamic polarization curves were used to assess the corrosion resistance before and after coating. The penetration depth of silane was measured visually, and the Vickers hardness test was used for the silicate penetrant. The “equivalent cover approach” was adopted to evaluate the performance of penetrants throughout their service lives. Results revealed that the total corrosion current density decreased by 79% for specimens coated with silane and 52% for silicate penetrant, whereas no change was observed in the uncoated specimens. Based on the equivalent cover approach, the silane penetrant was determined to be most effective in delaying the corrosion onset and propagation time for cover thicknesses of 60 and 50 mm at 100 m distance against 70 mm, and for 40 and 30 mm against 50 mm at 250 m from the coastline. Further, the silicate-based penetrant was only effective for a deficient cover thickness of 5 mm against the specified cover thicknesses at a distance of 100 and 250 m from the sea coast. Doi: 10.28991/CEJ-2023-09-12-02 Full Text: PDF

Influence of CeO2 nanoparticles in the stability of electrodeposited Ni anodes for alkaline electrolysers

In Mexico, the National Electric System Development Program (PRODESEN 2022–2036) establishes the use of green hydrogen to be supplied in Combined Cycle Power Plants in a mixture of 70% CH4 and 30% H2 for electric energy generation. For those places where natural resources such as sun, wind, and water are available, the best option is to use alkaline electrolysers due to cost and lifetime. The oxygen evolution reaction (OER), which takes place at the anode, is the limiting factor in the performance of an alkaline electrolyser because large overpotentials are required to break the (O–H)- bond needed to form the double bond of the gaseous oxygen molecule (OO). Many studies under the initial research stage report using Ni–CeO2 as a promising catalyst toward OER, observing good catalytic activity and stability at low overpotentials. This work deposited electrodes with Ni and Ni–CeO2 films of 80 μm on AISI 304 Stainless steel substrates.A kinetic study was performed using linear sweep voltammetry to determine the Tafel slope of the OER. An electrolysis system was integrated with these anodic electrodes and tested for 500 h to determine the stability of films at real operating conditions using 15 wt% NaOH as electrolyte @ 0.5 A cm−2. A better OER activity of the modified Ni–CeO2 electrodes than Ni electrodes was obtained. Ni–CeO2 electrode shows an onset potential of 1.48 V, a potential of 1.56 V at 5 mA cm−2, and a Tafel slope of 75.71 mV dec−1, which is related to a reaction determining step in an oxidation process of (OH)− via the one-electron transfer to the surface which is partial cover by OH species adsorbed. In the studies with the electrolyser test system, the Ni electrodes with an electrodeposited film of 80 μm showed good stability, and the film remained on the surface electrode.On the other hand, the electrode modified with Ni–CeO2 showed instability and high overpotentials as 500 h were completed. The last is attributed to the low conductivity of CeO2 and the formation of the passive NiO/NiOH2 layer on the electrode surface, which is not easily detached due to the presence of CeO2. These results confirm the importance of conducting tests in an electrolyser under real conditions.

Confocal Ellipse Hough Transform for Polarization Compass in the Nonideal Atmosphere

The polarization compass is an autonomous, long-endurance compass technique that is intended for enhancing the environmental suitability of the integrated navigation systems. Numerous research on polarization compass is based on the single Rayleigh scattering model. However, the real atmosphere is usually non-ideal and does not conform to the ideal single Rayleigh scattering model. The single Rayleigh scattering model would have a constant error in a non-ideal sky with a certain partial cover. Compared with the single-scattering model, Hannay’s model with multi-scattering equations provides a better description of the polarization pattern in the real atmosphere. Thus, the ellipse Hough transform algorithm(EHT) is proposed in this study to extract neutral points from the polarization pattern based on Hannay’s model to correct the error mentioned above. To prove the effectiveness of ellipse Hough transform algorithm, several experiments have been carried out in the non-ideal sky. And experiment results show that the average error of solar zenith and azimuth angle of the Hough transform is less than 1° in non-ideal weather with 30% cover. In conclusion, the ellipse Hough transform improves the accuracy of the polarization compass by 50% in multi-scattering light with a partial coverage of the sky and enlarges the environmental suitability of the polarization compass.

Irrigation of protected pepper crops according to growth stage using dynamic evapotranspiration estimates increases the water use efficiency

Current knowledge on crop irrigation in greenhouses is limited, and most irrigation measures are based on evapotranspiration (ET) estimated using external climatic conditions. Moreover, crop water requirement estimation by the Penman-Monteith (PM) model assumes complete coverage of the soil by the plants and usually does not account for partial cover, which changes during the growth of annual crops. The main goals of the present research were: (i) to develop and apply irrigation demand estimates for greenhouse pepper crops during their growth, based on internal meteorological conditions and real-time plant characteristics; and (ii) to examine the effect of that irrigation on yield. Experiments were conducted during two consecutive seasons in greenhouse pepper crops in the Jordan Valley region of eastern Israel. Four irrigation treatments were applied based on four different ET models: (i) PM model for outside reference evapotranspiration based on the FAO56 methodology, also denoted as the commercial treatment; (ii) PMrb model for pepper plants, which is a standard PM model in which a boundary layer resistance replaces the aerodynamic resistance; (iii) Shuttleworth-Wallace Layer (SWL) model which considers the soil and plants as separate interactive layers; (iv) Shuttleworth-Wallace Patch (SWP) model which considers the soil and plants as independent patches. The commercial treatment used external climatic conditions from a nearby meteorological station, whereas the other three treatments used internal meteorological conditions measured inside the greenhouse. Results showed a high correlation (R2 > 0.88) between leaf area index, vegetation cover fraction, and plant height during plant growth. Using the same meteorological conditions inside the greenhouse, the seasonal ET estimated by the PMrb model, which considers full vegetation cover, was larger by 21-28% than the SWL and SWP models, which consider the partial plant cover. Irrigation doses were deduced from ET multiplied by crop coefficients derived in a previous study for the same crop and structures. Using average data of the two seasons, we found that seasonal irrigation based on the two SW models was lower by 5-15% than that based on PMrb, and by 35-42% than the commercial irrigation. The water use efficiency of the commercial treatment was the lowest, while for the other treatments it was about 0.02 ton m-3 and higher by about 40% than the commercial. We conclude that irrigation of annual crops based on partitioning ET into evaporation and transpiration based on crop coverage and using internal climatic conditions allows water-savings without significant yield loss.

Improving soil organic carbon predictions from a Sentinel–2 soil composite by assessing surface conditions and uncertainties

Soil organic carbon (SOC) prediction from remote sensing is often hindered by disturbing factors at the soil surface, such as photosynthetic active and non–photosynthetic active vegetation, variation in soil moisture or surface roughness. With the increasing amount of freely available satellite data, recent studies have focused on stabilizing the soil reflectance by building reflectance composites using time series of images. Although composite imagery has demonstrated its potential in SOC prediction, it is still not well established if the resulting composite spectra mirror the reflectance fingerprint of the optimal conditions to predict topsoil properties (i.e. a smooth, dry and bare soil).We have collected 303 photos of soil surfaces in the Belgian loam belt where five main classes of surface conditions were distinguished: smooth seeded soils, soil crusts, partial cover by a growing crop, moist soils and crop residue cover. Reflectance spectra were then extracted from the Sentinel–2 images coinciding with the date of the photos. After the growing crop was removed by an NDVI < 0.25, the Normalized Burn Ratio (NBR2) was calculated to characterize the soil surface, and a threshold of NBR2 < 0.05 was found to be able to separate dry bare soils from soils in unfavorable conditions i.e. wet soils and soils covered by crop residues. Additionally, we found that normalizing the spectra (i.e. dividing the reflectance of each band by the mean reflectance of all spectral bands) allows for cancelling the albedo shift between soil crusts and smooth soils in seed–bed conditions. We then built the exposed soil composite from Sentinel–2 imagery for southern Belgium and part of Noord-Holland and Flevoland in the Netherlands (covering the spring periods of 2016–2021). We used the mean spectra per pixel to predict SOC content by means of a Partial Least Squares Regression Model (PLSR) with 10–fold cross–validation. The uncertainty of the models was assessed via the prediction interval ratio (PIR). The cross validation of the model gave satisfactory results (mean of 100 bootstraps: model efficiency coefficient (MEC) = 0.48 ± 0.07, RMSE = 3.5 ± 0.3 g C kg–1, RPD = 1.4 ±0.1 and RPIQ = 1.9 ± 0.3). The resulting SOC prediction maps show that the uncertainty of prediction decreases when the number of scenes per pixel increases, and reaches a minimum when at least six scenes per pixel are used (mean PIR of all pixels is 12.4 g C kg–1, while mean SOC predicted is 14.1 g C kg–1). The results of a validation against an independent data set showed a median difference of 0.5 g C kg–1 ± 2.8 g C kg–1 SOC between the measured (average SOC content 13.5 g C kg–1) and predicted SOC contents at field scale. Overall, this compositing method shows both realistic within field and regional SOC patterns.

Efficacy and Safety of Endoscopic Stenting for Crohn's Disease Related Strictures: A Systematic Review and Meta-analysis.

Endoscopic stenting is an evolving treatment for symptomatic Crohn's strictures. Several case series and small studies have reported its efficacy. Future studies can be designed based on a systematic review of the evaluation of efficacy. Hence, this meta-analysis was conducted to assess the critical role of stents in the management of intestinal strictures associated with Crohn's disease (CD). A literature search of various databases from 2000 to February 2022 was conducted for studies evaluating the outcome of stents in patients with CD-related stricture. The outcomes assessed included technical and clinical success, adverse events, symptom recurrence, and the need for a surgical resection. Pooled event rates across studies were expressed with summative statistics. Ten studies with 170 patients were included in the present analysis. The pooled event rates for technical success, clinical success, stent migration, and post-procedural pain were 98.2% (95% CI, 95.8-100), 71.3% (95% CI, 57.4-85.1), 32% (95% CI, 0.0-65.3) and 20.2% (95% CI, 4.1-36.2), respectively. The cumulative recurrence rate and need for surgery were 40.1% (95% CI, 20.3-59.9) and 8.6% (95% CI, 1.7-15.5), respectively. Subgroup analysis showed that partially-covered (PC) self-expanding metallic stent (SEMS) was significantly better than fully-covered SEMS with a lower stent migration rate and symptom recurrence rate. Overall efficacy of stents in the management of CD-related stricture remains moderate with a low complication rate. Among the stents, PC-SEMS may be associated with a more favorable outcome. Future studies will be needed to determine the long-term benefits of endoscopic stenting.

Computing Maximal Covers for Protein Sequences.

A partial cover of a string or sequence of length n, which we model as an array , is a repeating substring u of x such that "many" positions in x lie within occurrences of u. A maximal cover u*-introduced in 2018 by Mhaskar and Smyth as optimal cover-is a partial cover that, over all partial covers u, maximizes the positions covered. Applying data structures also introduced by Mhaskar and Smyth, our software MAXCOVER for the first time enables efficient computation of u* for any x-in particular, as described here, for protein sequences of Arabidopsis, Caenorhabditis elegans, Drosophila melanogaster, and humans. In this protein context, we also compare an extended version of MAXCOVER with existing software (MUMmer's repeat-match) for the closely related task of computing non-extendible repeating substrings (a.k.a. maximal repeats). In practice, MAXCOVER is an order-of-magnitude faster than MUMmer, with much lower space requirements, while producing more compact output that, nevertheless, yields a more exact and user-friendly specification of the repeats.

(Oxy)nitride heterojunction-strengthened separation of photogenerated carriers in g-C3N4 towards enhanced photocatalytic H2 evolution

The metal-free graphitic carbon nitride (g-C3N4) with a series of merits like low cost, favorable stability, and controllable two-dimensional graphite-like structure, has been extensively studied for photocatalytic H2 evolution. Composite engineering is regarded as one of effective strategies to adjust the kinetics of photogenerated carriers in g-C3N4 for elevating its photocatalytic performance. Herein, the composite system of g-C3N4 with oxynitride LaTiO2N was elaborately constructed for improving photocatalytic H2-evolution performance. With systematical characterizations, the partial cover of g-C3N4 nanosheets on LaTiO2N (LaTiO2N@g-C3N4) was verified and promoted the sufficient contact between g-C3N4 and LaTiO2N, accompanied by the formation of the (oxy)nitride heterojunction. Benefited by the well-matched band structures for g-C3N4 and LaTiO2N, the (oxy)nitride heterojunction strengthened the separation of photogenerated carriers and therefore enhanced the photocatalytic performance of g-C3N4. This work gives more insight in composite engineering on g-C3N4, and also provides feasible guidelines for designing g-C3N4-based photocatalysts towards improving photocatalytic performance.

A note on the minimum power partial cover problem on the plane

A note on the minimum power partial cover problem on the plane

Modeling subgrid lake energy balance in ORCHIDEE terrestrial scheme using the FLake lake model

Abstract. The freshwater 1-D FLake lake model was coupled to the ORCHIDEE land surface model to simulate lake energy balance at the global scale. A multi-tile approach has been chosen to allow the modeling of various types of lakes within the ORCHIDEE grid cell. Thus, three different lake tiles have been defined according to lake depth which is the most influential parameter of FLake, but other properties could be considered in the future. Several depth parameterization strategies have been compared, differing by the way to aggregate the depth of the subgrid lakes, i.e., arithmetical, geometrical, harmonical mean and median. Five atmospheric reanalysis datasets available at 0.5∘ or 0.25∘ resolution have been used to force the model and assess model systematic errors. Simulations have been performed, evaluated and intercompared against observations of lake water surface temperatures provided by the GloboLakes database over about 1000 lakes and ice phenology derived from the Global Lake and River Ice Phenology database. The results highlighted the large impact of the atmospheric forcing on the lake energy budget simulations and the improvements brought by the highest resolution products (ERA5 and E2OFD). The median of the root square mean errors (RMSEs) calculated at global scale ranges between 3.2 and 2.7 ∘C among the forcings, CRUJRA and ERA5 leading respectively to the worst and best results. The depth parameterization strategy appeared to be less influential, with RMSE differences less than 0.1 ∘C for the four aggregation scenarios tested. The simulation of ice phenology presented systematic errors whatever the forcing and the depth parameterization used. Large systematic errors were highlighted such as negative biases on the onset and positive biases on the offset. Freezing onset was shown to be the less sensitive to atmospheric forcing with the median of the errors ranging between 10 and 14 d. Larger errors up to 25 d were observed on the simulation of the end of the freezing period. Such errors, already highlighted in previous works, could be explained by scale effects and deficiencies in the modeling of snow–ice processes not accounting for partial ice cover. Various pathways are drawn to improve the model results, including the use of remote sensing data to better constrain the lake radiative parameters (albedo and extinction coefficient) as well as the lake depth thanks to the recent and forthcoming high-resolution satellite missions.

${\boldsymbol~k}$-prize-collecting minimum power cover problem with submodular penalties on a plane

Given a set of $n$ points, a set of $m$ sensors on a plane, and a positive integer $k$ ($\leq~n$).Each sensor $s$ can adjust its power $p(s)$ and covering range, which is a disk of radius $r(s)$ satisfying $p(s)=r(s)^{\alpha}$, where $\alpha\geq~1$ is called the attenuation factor of power. The $k$-prize-collecting minimum power cover problem with submodular penalties on a plane determines a power assignmentsuch that at least $k$ users are covered. The goal is to minimize the overall power of the power assignment plus the penalty of the uncovered user set, where the penalty is determined by a submodular function. This problem generalizes the well-known minimum power cover problem, minimum power partial cover problem, and $k$-prize-collecting minimum power cover problem.Based on the geometric properties of the semi-disjoint disk set and primal-dual method, we present a two-phase $(5\cdot~2^{\alpha}+1)$-approximation algorithm. When the penalty function is linear, the approximation ratio of our algorithm is at most $5\cdot~2^{\alpha}$.

Observation of ultracold atomic bubbles in orbital microgravity.

Substantial leaps in the understanding of quantum systems have been driven by exploring geometry, topology, dimensionality and interactions in ultracold atomic ensembles1-6. A system where atoms evolve while confined on an ellipsoidal surface represents a heretofore unexplored geometry and topology. Realizing an ultracold bubble-potentially Bose-Einstein condensed-relates to areas of interest including quantized-vortex flow constrained to a closed surface topology, collective modes and self-interference via bubble expansion7-17. Large ultracold bubbles, created by inflating smaller condensates, directly tie into Hubble-analogue expansion physics18-20. Here we report observations from the NASA Cold Atom Lab21 facility onboard the International Space Station of bubbles of ultracold atoms created using a radiofrequency-dressing protocol. We observe bubble configurations of varying size and initial temperature, and explore bubble thermodynamics, demonstrating substantial cooling associated with inflation. We achieve partial coverings of bubble traps greater than one millimetre in size with ultracold films of inferred few-micrometre thickness, and we observe the dynamics of shell structures projected into free-evolving harmonic confinement. The observations are among the first measurements made with ultracold atoms in space, using perpetual freefall to explore quantum systems that are prohibitively difficult to create on Earth. This work heralds future studies (in orbital microgravity) of the Bose-Einstein condensed bubble, the character of its excitations and the role of topology in its evolution.

Simple interpretation of the seemingly complicated X-ray spectral variation of NGC 5548

ABSTRACT NGC 5548 is a very well-studied Seyfert 1 galaxy in broad wavelengths. Previous multiwavelength observation campaigns have indicated that its multiple absorbers are highly variable and complex. A previous study applied a two-zone partial covering model with different covering fractions to explain the complex X-ray spectral variation and reported a correlation between one of the covering fractions and the photon index of the power-law continuum. However, it is not straightforward to physically understand such a correlation. In this paper, we propose a model to avoid this unphysical situation; the central X-ray emission region is partially covered by clumpy absorbers composed of double layers. These ‘double partial coverings’ have precisely the same covering fraction. Based on our model, we have conducted an extensive spectral study using the data taken by XMM–Newton, Suzaku, and NuSTAR in the range of 0.3–78 keV for 16 yr. Consequently, we have found that the X-ray spectral variations are mainly explained by independent changes of the following three components; (1) the soft excess spectral component below ∼1 keV, (2) the cut-off power-law normalization, and (3) the partial covering fraction of the clumpy absorbers. In particular, spectral variations above ∼1 keV are mostly explained only by the changes of the partial covering fraction and the power-law normalization. In contrast, the photon index and all the other spectral parameters are not significantly variable.

Comparison of Two Analytic Energy Balance Models Shows Stable Partial Ice Cover Possible for Any Obliquity

Abstract In this study, we compare two analytic energy balance models with an explicit dependence on obliquity to study the likelihood of different stable ice configurations. We compare the results of models with different methods of heat transport and different insolation distributions. We show that stable partial ice cover is possible for any obliquity, provided the insolation distribution is sufficiently accurate. Additionally, we quantify the severity of the transition to the snowball state as different model parameters are varied. In accordance with an earlier study, transitions to the snowball state are more severe for higher values of the albedo contrast and energy transport across latitudes in both models; however, we find that the snowball transition is not equally likely across both models. This work is general enough to apply to any rapidly rotating planet and could be used to study the likelihood of snowball transitions on planets within the habitable region of other stars.