bluuebunny/crossref_metadata_2025 huggingface dataset:
Shear‐wave velocity structure from MASW and SPAC methods: The case of Adra town, SE Spain
Authors: Martínez‐Pagán Pedro , Navarro Manuel , Pérez‐Cuevas Jaruselsky , Alcalá Francisco J. , García‐Jerez Antonio , Vidal F. rancisco
Published: March 2020

The damage distribution in the town of Adra (south‐eastern Spain) during the 1993 and 1994 Adra earthquakes of magnitude Mw~5.0 and maximum intensity degree of VII (European Macroseismic Scale) was mainly concentrated in the southeast sector, where the low‐diagenetic (soft) sediments outcrop. As new urbanizations are being planned in this sector, a soil classification based on the shallow shear‐wave velocity () structure is needed. For the purpose of earthquake disaster mitigation, the Spatial Autocorrelation (SPAC) and the Multichannel Analysis of Surface Waves (MASW) methods were used to propose integrated 2D models for the seismic response characterization of the shallow geology. Joint inversion of H/V spectral ratios of ambient noise, interpreted under the Diffuse Field Approach and the dispersion curves derived from the SPAC method allowed us to obtain more constrained models. Both SPAC and MASW methods provided similar results for the surveyed geological formations. From these models, a classification of the geological formations was carried out in terms of values and Eurocode 8 (European Committee for Standardization ) classes. Lower values in the 180‐360 m/s range were found in the southeastern sector of the town, where soft sediments outcrop and some building damage was reported during the 1993‐1994 earthquakes. The highest values exceeding 800 m/s appear in the northern sector, where the hardest rocks outcrop and no building damage was reported. The combination of the well‐suited database prepared for different geological formations with the 1:5,000 scale geological mapping was an important step to obtain the detailed soil microzonation map of Adra. This approach offered a new predictive insight into the building damage distribution, which would contribute to the appropriate urban planning for the future growth of the town.
Let's Get a Two-Sided Platform Started
Authors: Trabucchi Daniel
Published: March 2020

Two-sided platforms are becoming more and more relevant in the modern economy, with leading examples like Airbnb or Uber. These companies can leverage several opportunities, which are intrinsic in their nature, but they also need to face severe challenges before reaching a critical mass and a mature stage. One of the greatest challenges is represented by the chicken and egg paradox, which refers to the need of the platform provider to convince both sides to join the platform even if it is worthless since the other side is not there. Previous studies provided examples of possible strategies to address it, but there is a lack of operational tactics that practitioners may use to direct tackle the challenges. Through the analysis of 16 case studies based on primary sources, this study presents seven tactics, then clusters in three groups. They are discussed according to previous literature drawing reflections on the characteristics of the two-sided platform and their business model implications.
Forced Convection Heat Transfer from a Pair of Circular Cylinders Confined in Ventilated Enclosure
Authors: Helmaoui Mustapha , Laidoudi Houssem , Belbachir Azzedine , Ayad Adel , Ghaniam Abedallah
Published: March 2020

This paper deals with a numerical simulation of laminar forced convection heat transfer from a pair of identical circular cylinders placed at the center of square cavity in the line array, the cavity is ventilated with single inlet and outlet ports, the inlet port is located at the middle of left vertical wall and the outlet port is located at the middle of right vertical wall. The work represents the effects of the distance between cylinders and Reynolds number on fluid flow and heat transfer rate. The governing equations of continuity, momentum and energy are solved by using finite-volume method. The obtained results are represented and discussed for following conditions: Reynolds number Re = 1 to 40, Prandtl number Pr = 7.01 and the gap distance S = 0.3L to 0.7L, where L is the cavity length. The main results are potted under the streamline and isotherm contours, the total drag coefficient and average Nusselt number of each cylinder is plotted versus studied parameters. It is found that the increase in the gap space distance between cylinders increases the heat transfer rate.
Finite Difference Investigation of a Polluted Non-Isothermal Variable-Viscosity Porous Media Flow
Authors: Nwaigwe Chinedu , Makinde Oluwole Daniel
Published: March 2020

We extend previous studies of channel flows to porous media flows with combined effects ofboth heat and mass transfer. We consider a temperaturedependent viscosity fluid and a concentrationdependent diffusivity in an unsteady and pressuredriven nonisothermal Brinkman flow. This leads to the governing equations for velocity, concentration and temperature. By lagging nonlinear coefficients, in time, a convergent finite difference scheme is formulated. We adopt the method of manufactured solutions to verify the convergence and second order spatial accuracy of the scheme. The impact of the flow parameters on the flow fields are numerically investigated. The results show that increase in the Darcy number and temperature parameter both increase the velocity while the increase in the pollutant diffusion parameter decreases the pollutant concentration.
Computational Analysis on Gas Turbine Blade by Hole Modified for Optimization the Effectiveness
Authors: Kebir Farouk
Published: March 2020

In order to reduce the operating costs of the engine, turbine designers must also increase the life of their components. However, high gas temperatures throughout the engine require more cooling air or better cooling efficiency to protect the parts from thermal damage. This study presents numerical research on cooling holes. Research focused on aerodynamics and thermal aspects of shallow whole angle. The numerical simulation is performed based on Reynolds Averaged Navier-Stokes (RANS) equations with SST turbulence model by using CFX. A modification has been done in the normal injection hole of 35°, by injecting the cold fluid at different blowing ratio, providing a significant change in the shape of holes which later we found in our numerical investigation giving good quality of film cooling effectiveness.
Dendritic Cells of Mesenteric and Regional Lymph Nodes Contribute to Yersinia enterocolitica O:3–Induced Reactive Arthritis in TNFRp55−/− Mice
Authors: Silva Juan E. , Mayordomo Andrea C. , Dave Mabel N. , Aguilera Merlo Claudia , Eliçabe Ricardo J. , Di Genaro María S.
Published: March 2020

Dendritic cells (DCs) participate in the pathogenesis of several diseases. We investigated DCs and the connection between mucosa and joints in a murine model of Yersinia enterocolitica O:3–induced reactive arthritis (ReA) in TNFRp55−/− mice. DCs of mesenteric lymph nodes (MLN) and joint regional lymph nodes (RLN) were analyzed in TNFRp55−/− and wild-type mice. On day 14 after Y. enterocolitica infection (arthritis onset), we found that under TNFRp55 deficiency, migratory (MHChighCD11c+) DCs increased significantly in RLN. Within these RLN, resident (MHCintCD11c+) DCs increased on days 14 and 21. Similar changes in both migratory and resident DCs were also detected on day 14 in MLN of TNFRp55−/− mice. In vitro, LPS-stimulated migratory TNFRp55−/− DCs of MLN increased IL-12/23p40 compared with wild-type mice. In addition, TNFRp55−/− bone marrow–derived DCs in a TNFRp55−/− MLN microenvironment exhibited higher expression of CCR7 after Y. enterocolitica infection. The major intestinal DC subsets (CD103+CD11b−, CD103−CD11b+, and CD103+CD11b+) were found in the RLN of Y. enterocolitica–infected TNFRp55−/− mice. Fingolimod (FTY720) treatment of Y. enterocolitica–infected mice reduced the CD11b− subset of migratory DCs in RLN of TNFRp55−/− mice and significantly suppressed the severity of ReA in these mice. This result was associated with decreased articular IL-12/23p40 and IFN-γ levels. In vitro FTY720 treatment downregulated CCR7 on Y. enterocolitica–infected bone marrow–derived DCs and purified MLN DCs, which may explain the mechanism underlying the impairment of DCs in RLN induced by FTY720. Taken together, data indicate the migration of intestinal DCs to RLN and the contribution of these cells in the immunopathogenesis of ReA, which may provide evidence for controlling this disease.
Natural T Cell Epitope Containing Methyl Lysines on Mycobacterial Heparin-Binding Hemagglutinin
Authors: Corbière Véronique , Segers Jérôme , Desmet Rémi , Lecher Sophie , Loyens Marc , Petit Emmanuelle , Melnyk Oleg , Locht Camille , Mascart Françoise
Published: March 2020

T cell epitopes are mostly nonmodified peptides, although posttranslationally modified peptide epitopes have been described, but they originated from viral or self-proteins. In this study, we provide evidence of a bacterial methylated T cell peptide epitope. The mycobacterial heparin-binding hemagglutinin (HBHA) is a protein Ag with a complex C-terminal methylation pattern and is recognized by T cells from humans latently infected with Mycobacterium tuberculosis. By comparing native HBHA with recombinant HBHA produced in Mycobacterium smegmatis (rHBHA-Ms), we could link antigenic differences to differences in the methylation profile. Peptide scan analyses led to the discovery of a peptide containing methyl lysines recognized by a mAb that binds to native HBHA ∼100-fold better than to rHBHA-Ms. This peptide was also recognized by T cells from latently infected humans, as evidenced by IFN-γ release upon peptide stimulation. The nonmethylated peptide did not induce IFN-γ, arguing that the methyl lysines are part of the T cell epitope.
The Eureka! by Kary Mullis
Authors: Gallus Lorenzo , Giammanco Marco , Mariottini Gian Luigi
Published: March 2020

Not available.
Understanding scoliosis
Authors: Dommisse G. F.
Published: March 2020

No abstract available.
Composition and mass size distribution of nitrated and oxygenated aromatic compounds in ambient particulate matter from southern and central Europe – implications for the origin
Authors: Kitanovski Zoran , Shahpoury Pourya , Samara Constantini , Voliotis Aristeidis , Lammel Gerhard
Published: March 2020

Abstract. Nitro-monoaromatic hydrocarbons (NMAHs), such as nitrocatechols,
nitrophenols and nitrosalicylic acids, are important constituents of
atmospheric particulate matter (PM) water-soluble organic carbon (WSOC) and
humic-like substances (HULIS). Nitrated and oxygenated derivatives of
polycyclic aromatic hydrocarbons (NPAHs and OPAHs) are toxic and ubiquitous in
the ambient air; due to their light absorption properties, together with
NMAHs, they are part of aerosol brown carbon (BrC). We investigated the
winter concentrations of these substance classes in size-resolved PM from
two urban sites in central and southern Europe, i.e. Mainz (MZ), Germany, and
Thessaloniki (TK), Greece. The total concentration of 11 NMAHs (∑11NMAH concentrations) measured in PM10 and total PM were
0.51–8.38 and 12.1–72.1 ng m−3 at the MZ and TK sites, respectively, whereas
∑7OPAHs were 47–1636 and 858–4306 pg m−3, and ∑8NPAHs were ≤90 and 76–578 pg m−3, respectively. NMAHs
contributed 0.4 % and 1.8 % to the HULIS mass at MZ and TK, respectively.
The mass size distributions of the individual substances generally peaked in
the smallest or second smallest size fraction i.e. <0.49
or 0.49–0.95 µm. The mass median diameter (MMD) of NMAHs was 0.10 and 0.27 µm at MZ and TK, respectively, while the MMDs of
NPAHs and OPAHs were both 0.06 µm at MZ and 0.12 and 0.10 µm
at TK. Correlation analysis between NMAHs, NPAHs, and OPAHs from one side and
WSOC, HULIS, sulfate, and potassium from the other suggested that fresh
biomass burning (BB) and fossil fuel combustion emissions dominated at the TK
site, while aged air masses were predominant at the MZ site.
Molecular compositions and optical properties of dissolved brown carbon in biomass burning, coal combustion, and vehicle emission aerosols illuminated by excitation–emission matrix spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry analysis
Authors: Tang Jiao , Li Jun , Su Tao , Han Yong , Mo Yangzhi , Jiang Hongxing , Cui Min , Jiang Bin , Chen Yingjun , Tang Jianhui , Song Jianzhong , Peng Ping'an , Zhang Gan
Published: March 2020

Abstract. Brown carbon (BrC) plays an essential impact on radiative forcing
due to its ability to absorb sunlight. In this study, the optical properties
and molecular characteristics of water-soluble and methanol-soluble organic
carbon (OC; MSOC) emitted from the simulated combustion of biomass and coal
fuels and vehicle emissions were investigated using ultraviolet–visible (UV–vis)
spectroscopy, excitation–emission matrix (EEM) spectroscopy, and
Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS)
coupled with electrospray ionization (ESI). The results showed that these
smoke aerosol samples from biomass burning (BB) and coal combustion (CC) had
a higher mass absorption efficiency at 365 nm (MAE365) than vehicle
emission samples. A stronger MAE365 value was also found in MSOC than
water-soluble organic carbon (WSOC), indicating low polar compounds would
possess a higher light absorption capacity. Parallel factor (PARAFAC) analysis
identified six types of fluorophores (P1–6) in WSOC including two
humic-like substances (HULIS-1) (P1 and P6), three protein-like substances
(PLOM) (P2, P3, and P5), and one undefined substance (P4). HULIS-1 was mainly from
aging vehicle exhaust particles; P2 was only abundant in BB aerosols; P3 was
ubiquitous in all tested aerosols; P4 was abundant in fossil burning
aerosols; and P5 was more intense in fresh vehicle exhaust particles. The
MSOC chromophores (six components; C1–6) exhibited consistent
characteristics with WSOC, suggesting the method could be used to indicate
the origins of chromophores. FT-ICR mass spectra showed that CHO and CHON
were the most abundant components of WSOC, but S-containing compounds
appeared in a higher abundance in CC aerosols and vehicle emissions than BB
aerosols, while considerably fewer S-containing compounds largely with CHO
and CHON were detected in MSOC. The unique formulas of different sources in the van Krevelen (VK) diagram presented different molecular distributions.
To be specific, BB aerosols with largely CHO and CHON had a medium H ∕ C and
low O ∕ C ratio, while CC aerosols and vehicle emissions largely with
S-containing compounds had an opposite H ∕ C and O ∕ C ratio. Moreover, the
light absorption capacity of WSOC and MSOC was positively associated with
the unsaturation degree and molecular weight in the source aerosols. The
above results are potentially applicable to further studies on the EEM-based or
molecular-characteristic-based source apportionment of chromophores in
atmospheric aerosols.
The impacts of biomass burning activities on convective systems over the Maritime Continent
Authors: Lee Hsiang-He , Wang Chien
Published: March 2020

Abstract. Convective precipitation associated with Sumatra squall lines and diurnal
rainfall over Borneo is an important weather feature of the Maritime
Continent in Southeast Asia. Over the past few decades, biomass burning
activities have been widespread during summertime over this region,
producing massive fire aerosols. These additional aerosols, when brought into the
atmosphere, besides influencing the local radiation budget through directly
scattering and absorbing sunlight, can also act as cloud condensation nuclei
or ice nuclei to alter convective clouds and precipitation over the Maritime
Continent via so-called aerosol indirect effects. Based on 4-month
simulations with or without biomass burning aerosols, conducted using the
Weather Research and Forecasting model coupled with a chemistry module (WRF-Chem), we
have investigated the aerosol–cloud interactions associated with biomass
burning aerosols over the Maritime Continent. Results from selected cases of
convective events have specifically shown the significant impact of fire aerosols
on weak convections by their increasing of the quantities of
hydrometeors and rainfall in both the Sumatra and Borneo regions. Statistical
analysis over the fire season also suggests that fire aerosols have impacts
on the nocturnal convections associated with the local anticyclonic
circulation in western Borneo and weaken nocturnal rainfall
intensity by about 9 %. Such an effect is likely to have come from the near-surface heating due to absorbing aerosols emitted from fires, which could weaken
land breezes and thus the convergence of anticyclonic circulation.
Measurements of carbonyl compounds around the Arabian Peninsula indicate large missing sources of acetaldehyde
Authors: Wang Nijing , Edtbauer Achim , Stönner Christof , Pozzer Andrea , Bourtsoukidis Efstratios , Ernle Lisa , Dienhart Dirk , Hottmann Bettina , Fischer Horst , Schuladen Jan , Crowley John N. , Paris Jean-Daniel , Lelieveld Jos , Williams Jonathan
Published: March 2020

Abstract. Volatile organic compounds (VOCs) were measured around the Arabian Peninsula using a research vessel during the AQABA campaign (Air Quality and Climate Change in the Arabian Basin) from June to August 2017. In this study we examine carbonyl compounds (CxHyO), measured by a proton transfer reaction mass spectrometer (PTR-ToF-MS), and present both a regional concentration distribution and a budget assessment for these key atmospheric species. Among the aliphatic carbonyls, acetone had the highest mixing ratios in most of the regions traversed, varying from 0.43 ppb over the Arabian Sea to 4.5 ppb over the Arabian Gulf, followed by formaldehyde (measured by Hantzsch monitor, 0.82 ppb over the Arabian Sea and 3.8 ppb over the Arabian Gulf) and acetaldehyde (0.16 ppb over the Arabian Sea and 1.7 ppb over the Arabian Gulf). Unsaturated carbonyls (C4–C9) varied from 10 to 700 ppt during the campaign, and followed similar regional mixing ratio dependence as aliphatic carbonyls, which were identified as oxidation products of cycloalkanes over polluted areas. An empirical method based on hydrocarbon ratios was applied to investigate the photochemical source strength of the aliphatic carbonyls. While the distribution and relative concentration enhancements of the C3–C8 aliphatic carbonyls could be explained by this method, that of acetaldehyde could not. A smaller but still significant discrepancy was found when comparing measurements to global chemistry-transport model (EMAC) results, with the model underestimating the measured acetaldehyde mixing ratio up to an order of magnitude. Implementing a photolytically driven marine source of acetaldehyde significantly improved the agreement between measurements and model, particularly over the remote regions (e.g. Arabian Sea). However, the newly introduced acetaldehyde source was still insufficient to describe the observations over the most polluted regions (Arabian Gulf and Suez), where model underestimation of primary emissions and biomass burning events are possible reasons.
Does a proxy measure up?: A framework to assess and convey proxy reliability
Authors: Boudinot F. Garrett , Wilson Joseph
Published: March 2020

Abstract. Earth scientists describe a wide range of observational measurements as “proxy measurements”. By referring to such a vast body of measurements simply as “proxy”, workers dilute significant differences in the various ways that measurements relate to the phenomena they intend to describe. The limited language around these measurements makes it difficult for the non-specialist to assess the reliability and uncertainty of data generated from “proxy” measurements. Producers and reviewers of proxy data need a common framework for conveying proxy measurement methodology, uncertainty, and applicability for a given study. We develop a functional distinction between different forms of measurement based on the different ways that their outputs (values, interpretations) relate to the phenomena they intend to describe (e.g., temperature). Paleothermometry measurements, which intend to represent the temperature of systems in Earth’s ancient past, are used as a case study to examine and apply this new functional proxy definition. We explore the historical development and application of two popular paleotemperature proxies, calcite δ18O and TEX86, to illustrate how different measurements relate to the phenomena they intend to describe. Both paleothermometers are vulnerable to causal factors that interfere with their relationship with temperature, but address those interfering causal factors in different ways. While the goal of proxy development is to fully identify, quantify, and calibrate to all confounding causal factors, the reality of proxy applications, especially for past systems, engenders unavoidable and potentially significant uncertainties. We propose a framework that allows researchers to be explicit about the limitations of their proxies, and identify steps for further development. This paper underscores the ongoing effort and continued need for critical examination of proxies throughout their development and application, particularly in Earth history, for reliable proxy interpretation.
Retrospect and prospect of a section-based stratigraphic and palaeontological database – Geobiodiversity Database
Authors: Xu Hong-He , Niu Zhi-Bin , Chen Yan-Sen
Published: March 2020

Abstract. Big data are significant to the quantitative analysis and contribute to the data-driven scientific research and discoveries. Here the thorough introduction is given on the Geobiodiversity database (GBDB), a comprehensive stratigraphic and palaeontological database. The GBDB includes abundant geological records from China and contributes a serial of scientific studies on early Palaeozoic palaeogeography, tectonic and biodiversity evolution of China. Nevertheless, the existing problems of the GBDB limited the using of its data. The turnover and improvement of the GBDB were started in 2019. Besides the data collecting, processing and visualization as the GBDB did previously, the database and the website are optimized and re-designed, the new GBDB working team pays more attention to data analyzing with the professional artificial intelligence techniques. GBDB is complementary to other related databases and further collaborations are proposed to mutually benefit and push forward the quantitative research of palaeontology and stratigraphy in the era of big data. The persistent snapshot of the GBDB data can be found at: http://doi.org/10.5281/zenodo.3667645 (Xu, 2020).
Assimilation of vegetation optical depth retrievals from passive microwave radiometry
Authors: Kumar Sujay V. , Holmes Thomas R. , Bindlish Rajat , de Jeu Richard , Peters-Lidard Christa
Published: March 2020

Abstract. Vegetation optical depth (VOD) retrievals from passive microwave sensors provide estimates of above-ground canopy biomass. This study presents the development and analysis of assimilating VOD retrievals from X-, C-, and L-band passive microwave instruments within the Noah-MP land surface model, over the Continental U.S. The results from this study demonstrate that the assimilation of VOD retrievals have a significant beneficial impact on the simulation of evapotranspiration and GPP, particularly over the agricultural areas of the U.S. The improvements in the water and carbon fluxes from the assimilation of VOD from X- and C-band sensors are found to be comparable to those obtained from the assimilation of vegetation indices from optical sensors. The study also quantifies the relative and joint impact of assimilating surface soil moisture and VOD from SMAP. The utility of soil moisture assimilation for improving ET is more significant over water limited regions, whereas VOD DA is more impactful over energy limited domains. The results also indicate that the independent information on moisture and vegetation states from SMAP can be simultaneously exploited through the joint assimilation of surface soil moisture and VOD. Since the passive microwave-based VOD retrievals are available in nearly all weather conditions, their use within data assimilation systems offers the ability to extend and improve the utility obtained from the use of optical/infrared based vegetation retrievals.
On the relation between avalanche occurrence and avalanche danger level
Authors: Schweizer Jürg , Mitterer Christoph , Techel Frank , Stoffel Andreas , Reuter Benjamin
Published: March 2020

Abstract. In many countries with seasonally snow-covered mountain
ranges warnings are issued to alert the public about imminent avalanche
danger, mostly employing an ordinal, five-level danger scale. However, as
avalanche danger cannot be measured, the characterization of avalanche
danger remains qualitative. The probability of avalanche occurrence in
combination with the expected avalanche type and size decide on the degree
of danger in a given forecast region (≳100 km2). To describe
avalanche occurrence probability, the snowpack stability and its spatial
distribution need to be assessed. To quantify the relation between avalanche
occurrence and avalanche danger level, we analyzed a large data set of
visually observed avalanches (13 918 in total) from the region of Davos
(eastern Swiss Alps, ∼300 km2), all with mapped
outlines, and we compared the avalanche activity to the forecast danger level
on the day of occurrence (3533 danger ratings). The number of avalanches per
day strongly increased with increasing danger level, confirming that not only
the release probability but also the frequency of locations with a weakness
in the snowpack where avalanches may initiate from increase within a
region. Avalanche size did not generally increase with increasing avalanche
danger level, suggesting that avalanche size may be of secondary importance
compared to snowpack stability and its distribution when assessing the
danger level. Moreover, the frequency of wet-snow avalanches was found to be
higher than the frequency of dry-snow avalanches for a given day and danger
level; also, wet-snow avalanches tended to be larger. This finding may
indicate that the danger scale is not used consistently with regard to
avalanche type. Even though observed avalanche occurrence and avalanche danger
level are subject to uncertainties, our findings on the characteristics of
avalanche activity suggest reworking the definitions of the European
avalanche danger scale. The description of the danger levels can be
improved, in particular by quantifying some of the many proportional
quantifiers. For instance, based on our analyses, “many avalanches”, expected
at danger level 4-High, means on the order of at least 10 avalanches per
100 km2. Whereas our data set is one of the most comprehensive,
visually observed avalanche records are known to be inherently incomplete so
that our results often refer to a lower limit and should be confirmed using
other similarly comprehensive data sets.
Variability scaling and consistency in airborne and satellite altimetry measurements of Arctic sea ice
Authors: Xu Shiming , Zhou Lu , Wang Bin
Published: March 2020

Abstract. Satellite and airborne remote sensing provide complementary capabilities for the observation of the sea ice cover.
However, due to the differences in footprint sizes and noise levels of the measurement techniques, as well as sea ice's variability across scales, it is challenging to carry out inter-comparison or consistently study these observations.
In this study we focus on the remote sensing of sea ice thickness parameters and carry out the following: (1) the analysis of variability and its statistical scaling for typical parameters and (2) the consistency study between airborne and satellite measurements.
By using collocating data between Operation IceBridge and CryoSat-2 (CS-2) in the Arctic, we show that consistency exists between the variability in radar freeboard estimations, although CryoSat-2 has higher noise levels.
Specifically, we notice that the noise levels vary among different CryoSat-2 products, and for the European Space Agency (ESA) CryoSat-2 freeboard product the noise levels are at about 14 and 20 cm for first-year ice (FYI) and multi-year ice (MYI), respectively.
On the other hand, for Operation IceBridge and NASA's Ice, Cloud, and land Elevation Satellite (ICESat), it is shown that the variability in snow (or total) freeboard is quantitatively comparable despite more than a 5-year time difference between the two datasets.
Furthermore, by using Operation IceBridge data, we also find widespread negative covariance between ice freeboard and snow depth, which only manifests on small spatial scales (40 m for first-year ice and about 80 to 120 m for multi-year ice).
This statistical relationship highlights that the snow cover reduces the overall topography of the ice cover.
Besides this, there is prevalent positive covariability between snow depth and snow freeboard across a wide range of spatial scales.
The variability and consistency analysis calls for more process-oriented observations and modeling activities to elucidate key processes governing snow–ice interaction and sea ice variability on various spatial scales.
The statistical results can also be utilized in improving both radar and laser altimetry as well as the validation of sea ice and snow prognostic models.
The firn meltwater Retention Model Intercomparison Project (RetMIP): Evaluation of nine firn models at four weather station sites on the Greenland ice sheet
Authors: Vandecrux Baptiste , Mottram Ruth , Langen Peter L. , Fausto Robert S. , Olesen Martin , Stevens C. Max , Verjans Vincent , Leeson Amber , Ligtenberg Stefan , Kuipers Munneke Peter , Marchenko Sergey , van Pelt Ward , Meyer Colin , Simonsen Sebastian B. , Heilig Achim , Samimi Samira , Machguth Horst , MacFerrin Michael , Niwano Masashi , Miller Olivia , Voss Clifford I. , Box Jason E.
Published: March 2020

Abstract. Perennial snow, or firn, covers 80 % of the Greenland ice sheet and has the capacity to retain part of the surface meltwater, buffering the ice sheet’s contribution to sea level. Multi-layer firn models are traditionally used to simulate the firn processes and estimate meltwater retention. We present the output from nine firn models, forced by weather-station-derived mass and energy fluxes at four sites representative of the dry snow, percolation, ice slab and firn aquifer areas. We compare the model outputs and evaluate them against in situ observations. Models that explicitly account for deep meltwater percolation overestimate percolation depth and consequently firn temperature at the percolation and ice slab sites although they accurately simulate the recharge of the firn aquifer. Models using Darcy's law and a bucket scheme compare favourably to observations at the percolation site but only the Darcy models accurately simulate firn temperature and thus meltwater percolation at the ice slab site. We find that Eulerian models, that transfer firn through fixed layers, smooth sharp gradients in firn temperature and density over time. From the model spread, we find that simulated densities (respectively temperature) have an uncertainty envelope of ±60 kg m−3 (resp. ±14 °C) in the dry snow area and up to ±280 kg m−3 (resp. ±15–18 °C) at warmer sites.
Representative surface snow density on the East Antarctic Plateau
Authors: Weinhart Alexander H. , Freitag Johannes , Hörhold Maria , Kipfstuhl Sepp , Eisen Olaf
Published: March 2020

Abstract. Surface mass balance estimates of polar ice sheets are essential to estimate the contribution of ice sheets to sea level rise, in response global warming. One of the largest uncertainties in the interior regions of the ice sheets, such as the East Antarctic Plateau (EAP), is the determination of a precise surface snow density. Wrong estimates of snow and firn density can lead to significant underestimations of the surface mass balance. We present density data from snow profiles taken along an overland traverse in austral summer 2016/17 covering over 2000 km on the Dronning Maud Land plateau. The sampling strategy included investigation on various spatial scales, from regional to local, with sampling locations 100 km apart as well as a high-resolution study in a trench at 30° E 79° S with thirty 3 m deep snow profiles. Density of the surface snow profiles has been measured volumetrically as well as using μ-computer tomography. With an error of less than 2 %, the volumetric liner density provides higher precision than other sampling devices of smaller volume. With four spatially independent snow profiles per location we derive a representative and precise 1 m mean snow density with an error of less than 1.5 %. The average liner density along the traverse across the EAP is 355 kg m−3, which we identify as representative surface snow density between Kohnen station and Dome Fuji. The highest horizontal variability in density can be seen in the upper 0.3 m. Therefore, we do not recommend vertical sampling in intervals of less than several decimeters, as this does neither adequately cover seasonal variations in high accumulation areas nor the annual accumulation in low accumulation areas. From statistical analysis of the liner density on regional scale we identify representative spatial distributions of density based on geographical and thus climatic conditions. Our representative density of 355 kg m−3 is considerably different from the density of 320 kg m−3 provided by a regional climate model. This difference of more than 10 % indicates the necessity for further calibration of density parameterizations. The difference in the total mass equivalent of measured and modelled density yields a 3 % underestimation by models, which translates into 5 cm sea level equivalent. We do not find a statistically significant temporal trend in density changes over the last two decades. Our data provide a solid baseline for tuning parameterizations of the surface snow density for regions with low accumulation and low temperatures like the EAP to improve surface mass balance estimates of polar ice sheets.
A 14.5 million-year record of East Antarctic Ice Sheet
fluctuations from the central Transantarctic Mountains,
constrained with cosmogenic 3He, 10Be, 21Ne, and 26Al
Authors: Balter Allie , Bromley Gordon , Balco Greg , Thomas Holly , Jackson Margaret S.
Published: March 2020

Abstract. The distribution of moraines in the Transantarctic Mountains affords direct constraint of past ice-marginal positions of the East Antarctic Ice Sheet (EAIS). Here, we describe glacial-geologic observations and cosmogenic-nuclide exposure ages from Roberts Massif, an ice-free area in the central Transantarctic Mountains. We measured cosmogenic 3He, 10Be, 21Ne, and 26Al in 180 dolerite and sandstone boulders collected from 24 distinct deposits. Our data show that a cold-based EAIS was present, in a configuration similar to today, for many periods over the last ~ 14.5 Myr, including the mid-Miocene, Late Pliocene, and early-to-mid Pleistocene. Moraine ages at Roberts Massif increase with distance from, and elevation above the modern ice margin, which is consistent with a persistent EAIS extent during glacial maxima, and slow, isostatic uplift of the massif itself in response to trough incision by outlet glaciers. We also employ the exceptionally high cosmogenic-nuclide concentrations in several boulders, along with multi-isotope measurements in sandstone boulders, to infer extremely low erosion rates (
The Safety of Women and Girls in Educational Settings: A Global Overview and Suggestions for Policy Change
Authors: Behounek Elaina
Published: March 2020

Safety in educational settings is a barrier to equality for women and girls. This article highlights four key areas that perpetuate inequality in education for women and girls, and that contribute to a worldwide lack of safety in educational settings for women and girls: cultural norms, societal norms, sexual assault and sexual harassment. All four areas form part of a social–structural condition that underpins a world in which women and girls experience violence and an economic and social inequality that contributes to their lack of safety in educational settings. Several solutions are proposed to combat this. To improve the life outcomes of women and girls, we must invest in approaches that empower and educate them in safe environments. In doing so, we must also ensure that such approaches are holistic and intersectional.
Protections for Marginalised Women in University Sexual Violence Policies
Authors: Roskin-Frazee Amelia
Published: March 2020

Higher education institutions in four of the top 20 wealthiest nations globally (measured by GDP per capita) undermine gender equality by failing to address sexual violence perpetrated against women with marginalised identities. By analysing student sexual violence policies from 80 higher education institutions in Australia, Canada, the United Kingdom, and the United States, I argue that these policies fail to account for the ways that race, sexuality, class and disability shape women’s experiences of sexual violence. Further, these deficiencies counteract efforts to achieve gender equality by tacitly denying women who experience violence access to education and health care. The conclusion proposes policy alterations designed to address the complex needs of women with marginalised identities who experience violence, including implementing cultural competency training and increasing institution-sponsored health care services for sexual violence survivors.
Fostering Family Relationships and Women’s Employment
Authors: Leverentz Andrea
Published: March 2020

Although people in prison share some commonalities, they also face distinct issues based on who they are and where they are incarcerated. In this article, I offer suggestions regarding re-entry programs and policies for women. I frame these policies through a broader lens of intersectionality and the importance of context. People are embedded in interlocking systems of power, and experiences and positionality are shaped along multiple dimensions. Additionally, to understand criminal justice responses, we must understand the local social, political and economic contexts, as these programs may not translate across jurisdictions if local considerations are not taken into account. Just as crime and criminal justice policies are embedded in larger social worlds, so too are re-entry programs. Three policy areas are considered within this larger framework: drug courts, family reunification and employment.
Digital nomads, coworking, and other expressions of mobile work on Twitter
Authors: Hemsley Jeff , Erickson Ingrid , Jarrahi Mohammad Hossein , Karami Amir
Published: March 2020

We analyze a set of Twitter hashtags to ascertain how contemporary parlance in social media can illuminate the rich cultural intersections between modern forms of work, use of technology, and physical mobility. We use network word co-occurrence analysis and topic modeling to reveal several thematic areas of discourse present in Twitter, each with its own affiliated terms and distinctive emphases. The first theme centers on worker identity and is currently dominated by the experiences of digital nomads. The second theme focuses on the practicalities of working in a physical location and is currently dominated by issues related to co-working spaces. Finally, the third theme is a loose and speculative set of ideas around the evolution of work in the future, predicting how enterprises may have to adapt to new ways of working. Our contribution is twofold. First, we contribute to scholarship on social media methods by showing how a robust analysis of Twitter data can help scholars find subthematic nuance within a complex discussion space by identifying the existence and boundaries of topical sub-themes. Second, we contribute to scholarship on the future of work by providing empirical evidence for the ways that the myriad terms related to mobility and work relate to one another and, most importantly, how these relations signal semantic centrality among those who share their thoughts on these types of work.
Violence begetting violence: An examination of extremist content on deep Web social networks
Authors: Malevich Simon , Robertson Tom
Published: March 2020

Several incidents of mass violence in 2019 were preceded by manifestoes posted to deep Web social media sites by their perpetrators. These sites, most notably 4chan and 8chan, are buried in the deep Web, away from the neutralizing effects of broad public discourse. Many of the posts to these sites reference earlier extremist incidents, and indeed the incidents themselves mimic aspects of previous attacks. Building on previous research, this paper examines these deep Web social media sites. Through an analysis of traffic and posts, we confirm that these sites often act as a self-reinforcing community of users encouraging each other to violence, and we map a statistically significant rise in ”post volume” on these sites immediately following terrorist attacks.
Análisis de un poema de Manuel Gutiérrez Nájera: La duquesa Job explicada
Authors: González Huguet Carmen
Published: March 2020

El futuro periodista, escritor, cirujano y poeta Manuel Gutiérrez Nájera nació en la ciudad de México, en la calle del Esclavo número 2, hoy calle República de Chile número 13, el 22 de diciembre de 1859. Perteneciente a una familia de clase media, fue el primogénito del matrimonio de Manuel Gutiérrez de Salceda Gómez (1818-1889), y María Dolores Nájera Huerta (1831-1895). Lo bautizaron en la Iglesia del Sagrario Metropolitano con los nombres de Manuel Demetrio Francisco de Paula de la Santísima Trinidad Guadalupe Ignacio Antonio Miguel Joaquín, el día 4 de enero de 1860. Sus padrinos fueron el futuro funcionario José Yves Limantour Marquet (1854-1935), político y principal financiero del período conocido como porfiriato, y los tíos del futuro poeta: José Nájera Huerta y María Gertrudis Gutiérrez. Hay que hacer notar que el flamante padrino Limantour contaba escasos cinco años de edad cuando su ahijado fue bautizado.
El difícil camino a la ordenación urbana del Área Metropolitana de San Salvador: una revisión crítica a los planes urbanos del AMSS 1953-1997
Authors: Chicas Molina Juan Carlos
Published: March 2020

Se analizan tres de los principales planes urbanos elaborados para el Área Metropolitana de San Salvador (AMSS), identificando aquellos elementos componentes que configuraron la metrópolis salvadoreña. Se inicia con la propuesta de 1953, donde se propuso la estructuración de la ciudad por un sistema articulado de centros de barrio interconectado por un sistema vial moderno. Seguidamente, se examina METROPLAN 80 (1968), el cual abordó la estructuración de la ciudad desde una visión económica imperante en la época de fuerte planificación estatal. Finalmente, se revisa el plan PLAMADUR-AMSSA (1996), el cual propuso una redensificación del núcleo central de la ciudad, con miras a una ciudad compacta. Se concluye que el camino de gestión urbana del AMSS, ha seguido la dinámica al igual que la mayoría de las ciudades de la región, signada por las particularidades económicas, sociales y ambientales propias.
Amlodipine causing symptomatic bradycardia in a healthy 71-year-old male
Authors: Tu Angie , Adjovu Seth Kabutey
Published: March 2020

Amlodipine is a calcium channel blocker that is well known to be vasoselective, thereby having minimal effects in cardiac tissue. However, recent literature have reported cases of symptomatic bradycardia associated with amlodipine use. We present a case of an otherwise healthy 71-year-old male who was found to have symptomatic bradycardia while taking amlodipine. He underwent comprehensive evaluation including an exercise stress echocardiogram during which he demonstrated chronotropic competence. Amlodipine was discontinued with return of his heart rate to baseline levels after 24 hours. There is a very low reported incidence of amlodipine-induced bradycardia (0.89% of cases). Despite its infrequency, it is important to recognize amlodipine-induced bradycardia as simply discontinuing the drug will lead to complete resolution of symptoms. Failure to recognize this side effect may lead to unnecessary healthcare costs and negatively impact patient outcomes.
Addition of Bone Marrow Stem Cells Therapy Achieves Better Clinical Outcomes and Lower Rates of Disease Progression Compared With Core Decompression Alone for Early Stage Osteonecrosis of the Femoral Head: A Systematic Review and Meta-Analysis
Authors: Zhang Chaofan , Fang Xinyu , Huang Zida , Li Wenbo , Zhang Wenming , Lee Gwo-Chin
Published: March 2020

Background:

Osteonecrosis of the femoral head (ONFH) is a cause of hip pain and early joint arthrosis in the young patient. Nonarthroplasty interventions aim to decompress vascular congestion in the femoral head and stimulate new bone growth to prevent progression and collapse. Therefore, the purpose of this study is to evaluate the available evidence on the effect of adjuvant bone marrow stem cells (BMSCs) for early stage ONFH.

Methods:

We performed a systematic review of the MEDLINE, PubMed, Embase, and Cochrane databases in search of published reports comparing the core decompression (CD) with/without adjuvant BMSCs for ONFH. The cohort was divided into two groups: (1) CD with BMSCs (intervention) and (2) CD alone (control subject). The various outcome parameters including hip pain and function, progression of ONFH, rate of revision surgeries, and complications were analyzed. Data were extracted and aggregated for meta-analysis. Cases with staging beyond Ficat II, UPENN II, or ARCO II were excluded.

Results:

Of the published reports, 16 met our inclusion criteria with an aggregated 583 hips in the intervention and 468 hips in the control subject groups, respectively. Addition of bone marrow cells to CD resulted in lower hip pain score (VAS) (MD = −10.88, 95% CI = −16.84 to −4.92, P = 0.003) and higher HHS score (MD = 5.59, 95% CI = 1.13 to 10.04, P = 0.01) compared with CD alone at the 24-month follow-up. For rates of progression to higher stages, 138 progressed in the intervention group compared with 202 in the control subject group (P = 0.0002). Finally, subsequent patients who required total hip arthroplasty surgery were lower in the intervention group (22.5% versus 42.3%, P = 0.001).

Conclusions:

Despite heterogeneous and poor data, there is evidence that addition of bone marrow cells to CD appears to result in better clinical outcomes and lower rates of disease progression compared with cored decompression alone.

Level of Evidence:

Therapeutic Level III
Una investigación sobre la evolución del conocimiento didáctico del profesorado sobre la evaluación en Ciencias
Authors: Lopez-Lozano Lidia , Solís Ramírez Emilio
Published: March 2020

Presentamos un trabajo para investigar los procesos de cambio en el conocimiento didáctico del profesorado en formación sobre la evaluación en Ciencias. Se aplica una metodología mixta bajo un diseño concurrente con técnicas cualitativas y cuantitativas utilizando un proceso de triangulación. Participan 347 estudiantes del Grado de Educación Primaria que cursan la asignatura de Didáctica de las Ciencias Experimentales. Analizamos cuestionarios, guiones formativos y los diseños elaborados por dichos estudiantes. El procedimiento seguido se muestra valioso y útil para documentar la evolución experimentada del profesorado. Los resultados evidencian cambios relativos a una mayor coherencia entre el conocimiento declarativo y factual del profesorado al finalizar la formación estimulado en gran medida por la reflexión sobre su diseño.