bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular and spatial distributions of dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls in marine aerosols over the South China Sea to East Indian Ocean
Authors: Yang Jing , Zhao Wanyu , Wei Lianfang , Zhang Qiang , Zhao Yue , Hu Wei , Wu Libin , Li Xiaodong , Pavuluri Chandra Mouli , Pan Xiaole , Sun Yele , Wang Zifa , Liu Cong-Qiang , Kawamura Kimitaka , Fu Pingqing
Published: December 2019

Abstract. Marine aerosol samples collected from the South China Sea (SCS) to East Indian Ocean (EIO) during a cruise from March 10 to April 26, 2015 were studied for diacids and related compounds. In view of the air mass backward trajectories and source regions of geographical features, the cruise area is segregated into the South China Sea (SCS), the East Indian Ocean off the coast of western Indonesia (EIO-WI), the EIO off the coast of Sri Lanka (EIO-SL), Malacca and Sri Lanka docking point (SLDP). Total concentrations of diacids, oxoacids and α-dicarbonyls were much higher at SLDP followed by the SCS, Malacca, and the lowest at the EIO-WI. In this study, oxalic acid (C2) is the dominant diacid during the cruise, followed by malonic acid (C3) in the SCS, EIO-WI, EIO-SL and Malacca, whereas succinic acid (C4) diacid was relatively more abundant than C3 diacid in SLDP. Except for SLDP, C3/C4 mass ratios were always greater than 1, and no significant difference was observed among the cruise. The C2/C4 and C2/total diacids ratios also showed the similar trends. Average mass ratios of adipic acid (C6) to azelaic acid (C9) were less than unity except for at EIO-WI; the mass ratios of phthalic acid (Ph) to azelaic acid (C9) were less than 2 except for at SCS. The concentrations of diacids were higher when the air masses originated from the terrestrial regions than those from the remote oceanic regions. Based on the molecular distributions of organic acids, the mass ratios and linear correlations of selected compounds in each area, we found that the oxidation of biogenic volatile organic compounds (BVOCs) released from the ocean surface and subsequent photochemical oxidations were the main contributors to diacids, oxocarboxylic acids and α-dicarbonyls over the SCS to EIO. In addition, the continental outflow that enriched with the anthropogenic VOCs and their aging influenced the organic aerosol loading, particularly over the SCS. The emissions from local terrestrial vegetations as well as fossil fuel combustion and subsequent in-situ photochemical oxidation also played a prominent role in controlling the organic aerosols loading and molecular distributions of diacids and related compounds at SLDP.
Spatial distribution of enhanced BrO and its relation to meteorological parameters in Arctic and Antarctic sea ice regions
Authors: Seo Sora , Richter Andreas , Blechschmidt Anne-Marlene , Bougoudis Ilias , Burrows John Philip
Published: December 2019

Abstract. Satellite observations have shown large areas of elevated BrO covering several thousand km2 over the Arctic and Antarctic sea ice region in polar spring. These enhancements of total BrO columns result from increases in stratospheric or tropospheric bromine amounts or both, and their occurrence may be related to local meteorological conditions. In this study, the spatial distribution of the occurrence of total BrO column enhancements and the associated changes in meteorological parameters are investigated in both the Arctic and Antarctic regions using 10 years of GOME-2 measurements in combination with meteorological model data. Statistical analysis of the data presents clear differences in the meteorological conditions between the 10 year mean and episodes of enhanced total BrO columns in both polar sea ice regions. These differences show pronounced spatial patterns. In general, atmospheric low pressure, cold surface air temperature, high surface-level wind speed and low tropopause heights were found during periods of enhanced total BrO columns. In addition, spatial patterns of prevailing wind directions related to the BrO enhancements are identified in both the Arctic and Antarctic sea ice region. The relevance of the different meteorological parameters for the total BrO column is evaluated based on a Spearman rank correlation analysis, finding that tropopause height and surface air temperature have the largest correlations with the total BrO vertical column density. Our results demonstrate that specific meteorological parameters can have a major impact on the BrO enhancement in some areas, but in general, multiple meteorological parameters interact with each other in their influence on BrO columns.
Multi-scheme chemical ionization inlet (MION) for fast switching of reagent ion chemistry in atmospheric pressure chemical ionization mass spectrometry (CIMS) applications
Authors: Rissanen Matti P. , Mikkilä Jyri , Iyer Siddharth , Hakala Jani
Published: December 2019

Abstract. A novel chemical ionization inlet named the Multi-scheme chemical IONization inlet (MION), Karsa Ltd., Helsinki,
Finland) capable of fast switching between multiple reagent ion schemes is
presented, and its performance is demonstrated by measuring several known
oxidation products from much-studied cyclohexene and α-pinene
ozonolysis systems by applying consecutive bromide (Br−) and nitrate
(NO3-) chemical ionization. Experiments were performed in flow
tube reactors under atmospheric pressure and room temperature (22 ∘C) utilizing an atmospheric pressure interface time-of-flight mass spectrometer (APi-ToF-MS, Tofwerk Ltd., Thun, Switzerland) as the detector.
The application of complementary ion modes in probing the same steady-state
reaction mixture enabled a far more complete picture of the detailed
autoxidation process; the HO2 radical and the least-oxidized reaction
products were retrieved with Br− ionization, whereas the highest-oxidized reaction products were detected in the NO3- mode,
directly providing information on the first steps and on the ultimate endpoint of
oxidation, respectively. While chemical ionization inlets with multiple
reagent ion capabilities have been reported previously, an application in
which the charging of the sample occurs at atmospheric pressure with
practically no sample pretreatment, and with the potential to switch the
reagent ion scheme within a second timescale, has not been introduced
previously. Also, the ability of bromide ionization to detect
highly oxygenated organic molecules (HOM) from atmospheric autoxidation reactions has not been demonstrated
prior to this investigation.
Field comparison of dry deposition samplers for collection of atmospheric mineral dust: results from single-particle characterization
Authors: Waza Andebo , Schneiders Kilian , May Jan , Rodríguez Sergio , Epple Bernd , Kandler Konrad
Published: December 2019

Abstract. Frequently, passive dry deposition collectors are used to sample atmospheric
dust deposition. However, there exists a multitude of different instruments
with different, usually not well-characterized sampling efficiencies. As a
result, the acquired data might be considerably biased with respect to their
size representativity and, as a consequence, also composition. In this study,
individual particle analysis by automated scanning electron microscopy
coupled with energy-dispersive X-ray analysis was used to characterize different,
commonly used passive samplers with respect to their size-resolved
deposition rate and concentration. This study focuses on the microphysical
properties, i.e., the aerosol concentration and deposition rates as well as
the particle size distributions. In addition, computational fluid dynamics
modeling was used in parallel to achieve deposition velocities from a
theoretical point of view. Scanning electron microscopy (SEM)-calculated deposition rate measurements made using different passive
samplers show a disagreement among the samplers. Modified Wilson and Cooke
(MWAC) and Big Spring Number Eight (BSNE) – both horizontal flux samplers –
collect considerably more material than the flat plate and Sigma-2 samplers, which
are vertical flux samplers. The collection efficiency of MWAC increases for
large particles in comparison to Sigma-2 with increasing wind speed, while
such an increase is less observed in the case of BSNE. A positive
correlation is found between deposition rate and PM10 concentration
measurements by an optical particle spectrometer. The results indicate that
a BSNE and Sigma-2 can be good options for PM10 measurement, whereas
MWAC and flat-plate samplers are not a suitable choice. A negative
correlation was observed in between dust deposition rate and wind speed.
Deposition velocities calculated from different classical deposition models
do not agree with deposition velocities estimated using computational fluid
dynamics (CFD) simulations. The deposition velocity estimated from CFD was
often higher than the values derived from classical deposition velocity
models. Moreover, the modeled deposition velocity ratios between different
samplers do not agree with the observations.
Cryptic role of tetrathionate in the sulfur cycle: A study from Arabian Sea sediments
Authors: Mandal Subhrangshu , Bhattacharya Sabyasachi , Roy Chayan , Rameez Moidu Jameela , Sarkar Jagannath , Mapder Tarunendu , Fernandes Svetlana , Peketi Aditya , Mazumdar Aninda , Ghosh Wriddhiman
Published: December 2019

Abstract. To explore the potential role of tetrathionate in the sulfur cycle of marine sediments, population ecology of microorganisms capable of metabolizing this polythionate was revealed at 15–30 cm resolution along two, ~ 3-m-long, cores collected from 530 and 580 meters below the sea level, off India's west coast, within the oxygen minimum zone (OMZ) of the Arabian Sea. Metagenome analysis along the two sediment-cores revealed widespread occurrence of genes involved in microbial formation, oxidation, and reduction of tetrathionate; high diversity and relative-abundance was also detected for bacteria that are known to render these metabolisms in vitro. Results of slurry-incubation of the sediment-samples in thiosulfate- or tetrathionate-containing microbial growth media, data obtained via pure-culture isolation, and finally metatranscriptome analyses, corroborated the in situ functionality of tetrathionate-forming, oxidizing, and reducing microorganisms. Geochemical analyses revealed the presence of up to 11.1 µM thiosulfate along the two cores, except a few sample-sites near the sediment-surface. Thiosulfate oxidation by chemolithotrophic bacteria prevalent in situ is the apparent source of tetrathionate in this ecosystem. However, potential abiotic origin of the polythionate can neither be ruled out nor confirmed from the geochemical information currently available for this territory. Tetrathionate, in turn, can be either oxidized to sulfate (via oxidation by the chemolithotrophs present) or reduced back to thiosulfate (via respiration by native bacteria). Up to 2.01 mM sulfide present in the sediment-cores may also reduce tetrathionate abiotically to thiosulfate and elemental sulfur. As tetrathionate was not detected in situ, high microbiological and geochemical reactivity of this polythionate was hypothesized to be instrumental in its cryptic status as a central sulfur cycle intermediate.
Entrainment and suspension of sand and gravel
Authors: de Leeuw Jan , Lamb Michael P. , Parker Gary , Moodie Andrew J. , Haught Daniel , Venditti Jeremy G. , Nittrouer Jeffrey A.
Published: December 2019

Abstract. Entrainment and suspension of sand and gravel is important for the evolution of rivers, deltas, coastal areas and submarine fans. The prediction of a vertical profile of suspended sediment concentration typically consists of assessing (1) the concentration near the bed using an entrainment relation and (2) the upward vertical distribution of sediment in the water column. Considerable uncertainty exists in regard to both of these steps, and especially the near-bed concentration. Most entrainment theories have been tested against limited grain-size specific data, and no relations have been evaluated for gravel suspension, which can be important in bedrock and mountain rivers, as well as powerful turbidity currents. To address these issues, we compiled a database with suspended sediment data from natural rivers and flume experiments, taking advantage of the increasing availability of high-resolution grain-size measurements. We evaluated 14 dimensionless parameters that may determine entrainment and suspension relations, and applied multivariate regression analysis. A best-fit two-parameter equation (r2 = 0.79) shows that near-bed entrainment, evaluated at 10 % of the flow depth, increases with the ratio of skin-friction shear velocity to settling velocity (u*skin / wsi), as in previous relations, and with Froude number (Fr), possibly due to its role in determining bedload-layer concentrations. We used the Rouse equation to predict concentration upward from the reference level, and evaluated the coefficient βi, which accounts for differences between turbulent diffusivities of sediment and momentum. The best-fit relation for βi (r2 = 0.40) indicates greater relative sediment diffusivities for rivers with greater flow resistance, possibly due to bed-form induced turbulence, and smaller u*skin / wsi; the latter effect makes the dependence of Rouse number on u*skin / wsi nonlinear, and therefore different from standard Rousean theory. In addition, we used empirical relations for gravel saltation to show that our relation for near-bed concentration also provides good predictions for coarse-grained sediment. The new relations are a significant improvement compared to previous work, extend the calibrated parameter space over a wider range in sediment sizes and flow conditions, and result in 95 % of concentration data predicted within a factor of nine.
WAYS v1: a hydrological model for root zone water storage simulation on a global scale
Authors: Mao Ganquan , Liu Junguo
Published: December 2019

Abstract. The soil water stored in the root zone is a critical variable for many applications, as it plays a key role in several hydrological and atmospheric processes. Many studies have been conducted to obtain reliable information on soil water in the root zone layer. However, most of them are mainly focused on the soil moisture within a certain depth rather than the water stored in the entire rooting system. In this work, a hydrological model named the Water And ecosYstem Simulator (WAYS) is developed to simulate the root zone water storage (RZWS) on a global scale. The model is based on a well-validated lumped model and has now been extended to a distribution model. To reflect the natural spatial heterogeneity of the plant rooting system across the world, a key variable that influences RZWS, i.e., root zone storage capacity (RZSC), is integrated into the model. The newly developed model is first evaluated based on runoff and RZWS simulations across 10 major basins. The results show the ability of the model to mimic RZWS dynamics in most of the regions through comparison with proxy data, the normalized difference infrared index (NDII). The model is further evaluated against station observations, including flux tower and gauge data. Despite regional differences, generally good performance is found for both the evaporation and discharge simulations. Compared to existing hydrological models, WAYS's ability to resolve the field-scale spatial heterogeneity of RZSC and simulate RZWS may offer benefits for many applications, e.g., agriculture and land–vegetation–climate interaction investigations. However, the results from this study suggest an additional evaluation of RZWS is required for the regions where the NDII might not be the correct proxy.
Estimation of hydrological drought recovery based on GRACE water storage deficit
Authors: Singh Alka , Reager John T. , Behrangi Ali
Published: December 2019

Abstract. Drought is a natural climate extreme phenomenon that presents great challenges in forecasting and monitoring for water management purposes. Previous studies have examined the use of Gravity Recovery and Climate Experiment (GRACE) terrestrial water storage anomalies to measure the amount of water missing from a drought-affected region, and other studies have attempted statistical approaches to drought recovery forecasting based on joint probabilities of precipitation and soil moisture. The goal of this study is to combine GRACE data with historical precipitation observations to quantify the amount of precipitation required to achieve normal storage conditions in order to estimate a likely drought recovery time. First, linear relationships between terrestrial water storage anomaly (TWSA) and cumulative precipitation anomaly are established across a range of conditions. Then, historical precipitation data are statistically modeled to develop simplistic precipitation forecast skill. Three different precipitation scenarios are simulated by using a standard deviation in climatology. Precipitation scenarios are convolved with precipitation deficit estimates to calculate best-estimate of a drought recovery period. The results show that in the regions of strong seasonal amplitude (like monsoon belt) drought continues even with the above-normal precipitation until its wet season. Historical GRACE-observed drought recovery period is used to validate the approach. Estimated drought for an example month demonstrated 80% similar recovery period as observed by the GRACE.
Analysis of spatiotemporal variations in middle-tropospheric to upper-tropospheric methane during the Wenchuan Ms = 8.0 earthquake by three indices
Authors: Cui Jing , Shen Xuhui , Zhang Jingfa , Ma Weiyu , Chu Wei
Published: December 2019

Abstract. This research studied the spatiotemporal variation in methane in the middle to upper troposphere during the Wenchuan earthquake (12 May 2008) using AIRS retrieval data and discussed the methane anomaly mechanism.
Three indices were proposed and used for analysis. Our results show that the methane concentration increased significantly in 2008, with an average increase of 5.12×10-8, compared to the average increase of
1.18×10-8 in the previous 5 years. The absolute local index of change of the environment (ALICE) and differential value (diff) indices can be used to identify methane concentration anomalies. The two indices showed that the methane concentration distribution before and after
the earthquake broke the distribution features of the background field.
As the earthquake approached, areas of high methane concentration gradually
converged towards the west side of the epicenter from both ends of
the Longmenshan fault zone. Moreover, a large anomalous area was centered at the epicenter 8 d before the earthquake occurred, and a trend of strengthening, weakening and strengthening appeared over time.
The gradient index showed that the vertical direction obviously increased before the main earthquake and that the value was positive. The gradient value is negative during coseismic or post-seismic events. The gradient index reflects the gas emission characteristics to some extent. We also determined that the methane release was connected with the deep crust–mantle stress state, as well as micro-fracture generation and expansion. However, due to the lack of any technical means to accurately identify the source and content of methane in the atmosphere before the earthquake, an in-depth discussion has not been conducted, and further studies on this issue may be needed.
Nonlinear vortex solution for perturbations in the Earth’s Ionosphere
Authors: Vukcevic Miroslava , Popović Luka Č.
Published: December 2019

Abstract. There are many observational evidences of different fine structures in the ionosphere and magnetosphere of the Earth. Such structures are created and evolve as a perturbation of the ionosphere’s parameters. Instead of dealing with number of linear waves, we propose to investigate and follow up the perturbations in the ionosphere by dynamics of soliton structure. Apart of the fact that it is more accurate solution, the advantage of soliton solution is its localization in space and time as consequence of balance between nonlinearity and dispersion. The existence of such structure is driven by the properties of the medium. We derive necessary condition for having nonlinear soliton wave, taking the vortex shape, as description of ionosphere parameters perturbation. We employ magnetohydrodynamical description for the ionosphere in plane geometry, including rotational effects, magnetic field effects via ponderomotive force, pressure and gravitational potential effects, treating the problem self-consistently and nonlinearly. In addition, we consider compressible perturbation. As a result, we have obtained that Coriolis force and magnetic force at one side, and pressure and gravity on the other side, determine dispersive properties. Dispersion at higher latitudes is mainly driven by rotation, while near the equator, within the E and F-layer of ionosphere, magnetic field modifies the soliton solution. Also, very general description of the ionosphere results in the conclusion that the unperturbed thickness of the ionosphere layer cannot be taken as ad hoc assumption, it is rather consequence of equilibrium property, which is shown in this calculation.
Validating modeled critical crack length for crack propagation in the snow cover model SNOWPACK
Authors: Richter Bettina , Schweizer Jürg , Rotach Mathias W. , van Herwijnen Alec
Published: December 2019

Abstract. Observed snow stratigraphy and snow stability are of key importance for avalanche forecasting. Such observations are rare and snow cover models can improve the spatial and temporal resolution. To evaluate snow stability, failure initiation and crack propagation have to be considered. Recently, a new stability criterion relating to crack propagation, namely the critical crack length, was implemented into the snow cover model SNOWPACK. The critical crack length can also be measured in the field with a propagation saw test, which allows for an unambiguous comparison.
To validate and improve the parameterization for the critical crack length, we used data from 3 years of field experiments performed close to two automatic weather stations above Davos, Switzerland. We monitored seven distinct weak layers and performed in total 157 propagation saw tests on a weekly basis. Comparing modeled to measured critical crack length showed some discrepancies stemming from model assumption. Hence, we replaced two variables of the original parameterization, namely the weak layer shear modulus and thickness, with a fit factor depending on weak layer density and grain size. With these adjustments, the normalized root-mean-square error between modeled and observed critical crack lengths decreased from 1.80 to 0.28.
As the improved parameterization accounts for grain size, values of critical crack lengths for snow layers consisting of small grains, which in general are not weak layers, become larger. In turn, critical weak layers appear more prominently in the vertical profile of critical crack length simulated with SNOWPACK. Hence, minimal values in modeled critical crack length better match observed weak layers. The improved parameterization of critical crack length may be useful for both weak layer detection in simulated snow stratigraphy and also providing more realistic snow stability information – and hence may improve avalanche forecasting.
Optimization of over-summer snow storage at midlatitudes and low elevation
Authors: Weiss Hannah S. , Bierman Paul R. , Dubief Yves , Hamshaw Scott D.
Published: December 2019

Abstract. Climate change, including warmer winter temperatures, a
shortened snowfall season, and more rain-on-snow events, threatens nordic
skiing as a sport. In response, over-summer snow storage, attempted
primarily using woodchips as a cover material, has been successfully
employed as a climate change adaptation strategy by high-elevation and/or
high-latitude ski centers in Europe and Canada. Such storage has never been
attempted at a site that is both low elevation and midlatitude, and few
studies have quantified storage losses repeatedly through the summer. Such
data, along with tests of different cover strategies, are prerequisites to
optimizing snow storage strategies. Here, we assess the rate at which the
volume of two woodchip-covered snow piles (each ∼200 m3), emplaced during spring 2018 in Craftsbury, Vermont (45∘ N and
360 m a.s.l.), changed. We used these data to develop an optimized snow storage
strategy. In 2019, we tested that strategy on a much larger, 9300 m3
pile. In 2018, we continually logged air-to-snow temperature gradients under
different cover layers including rigid foam, open-cell foam, and woodchips
both with and without an underlying insulating blanket and an overlying
reflective cover. We also measured ground temperatures to a meter depth
adjacent to the snow piles and used a snow tube to measure snow density.
During both years, we monitored volume change over the melt season using
terrestrial laser scanning every 10–14 d from spring to fall. In 2018,
snow volume loss ranged from 0.29 to 2.81 m3 d−1, with the highest
rates in midsummer and lowest rates in the fall; mean rates of volumetric
change were 1.24 and 1.50 m3 d−1, 0.55 % to 0.72 % of initial
pile volume per day. Snow density did increase over time, but most volume
loss was the result of melting. Wet woodchips underlain by an insulating
blanket and covered with a reflective sheet were the most effective cover
combination for minimizing melt, likely because the aluminized surface
reflected incoming short-wave radiation while the wet woodchips provided
significant thermal mass, allowing much of the energy absorbed during the
day to be lost by long-wave emission at night. The importance of the pile
surface-area-to-volume ratio is demonstrated by 4-fold lower rates of
volumetric change for the 9300 m3 pile emplaced in 2019; it lost
<0.16 % of its initial volume per day between April and October,
retaining ∼60 % of the initial snow volume over summer. Together, these
data demonstrate the feasibility of over-summer snow storage at
midlatitudes and low elevations and suggest efficient cover strategies.
Spectral attenuation of gravity wave and model calibration in pack ice
Authors: Cheng Sukun , Stopa Justin , Ardhuin Fabrice , Shen Hayley H.
Published: December 2019

Abstract. We investigate an instance of wave propagation in the fall of 2015 in thin pack ice (<0.3 m) and use the resulting attenuation data to calibrate two viscoelastic wave-in-ice models that describe wave evolution. The study domain is 400 km by 300 km adjacent to a marginal ice zone (MIZ) in the Beaufort Sea. From Sentinel-1A synthetic aperture radar (SAR) imagery, the ice cover is divided into two regions delineated by the first appearance of leads. According to the quality of SAR retrievals, we focus on a range of wavenumbers corresponding to 9∼15 s waves from the open water dispersion relation. By pairing directional wave spectra from different locations, we obtain wavenumber-dependent attenuation rates, which slightly increase with increasing wavenumber before the first appearance of leads and become lower and more uniform against wavenumber in thicker ice after that. The results are used to calibrate two viscoelastic wave-in-ice models through optimization. For the Wang and Shen (2010) model, the calibrated equivalent shear modulus and viscosity of the pack ice are roughly one order of magnitude greater than that in grease/pancake ice reported in Cheng et al. (2017). These parameters obtained for the extended Fox and Squire model are much larger than laboratory values, as found in Mosig et al. (2015) using data from the Antarctic MIZ. This study shows a promising way of using remote sensing data with large areal coverage to conduct model calibration for various types of ice cover.
Relatos sobre maternidad, reproducción y crianza en la era post-televissión
Authors: Visa Barbosa Mariona
Published: December 2019

El objetivo de este estudio es analizar las ficciones televisivas contemporáneas protagonizadas por madres y centradas en el proceso de reproducción y crianza, con el fin de observar qué relatos se muestran de los procesos biológicos vinculados a la maternidad y de la etapa de la crianza. Después de siglos en los que la búsqueda del embarazo, la infertilidad, los abortos, la gestación, las pérdidas perinatales, el parto, la lactancia o el postparto han sido infrarrepresentados en las obras culturales, o tratados de forma simbólica sin incluir la subjetividad femenina, se observará si en la actualidad las reivindicaciones de género, la mayor producción de ficción y la facilidad de acceso a contenidos específicos han generado mayor pluralidad de discursos. A partir del análisis de contenido de cinco series estrenadas en los últimos años se detallarán sus características de producción, cuáles son las etapas de reproducción y crianza más representadas, las connotaciones que obtienen, las problemáticas que muestran y con qué perspectiva se abordan temas como la conciliación, el papel del padre, las relaciones familiares y los cambios en el cuerpo. El estudio concluye que la digitalización y la distribución de contenidos en streaming ha propiciado un aumento de obras que se centran en la etapa de reproducción, que existe una clara relación entre el aumento de mujeres en los equipos creativos y la mayor exploración de estas temáticas y que en ellas se representa la maternidad de forma diversa, incluyendo la descripción detallada de etapas vitales que no habían tenido cabida en la ficción televisiva con anterioridad.
DVT prophylaxis in critical care: role of NOACS
Authors: Lancé Marcus D.
Published: December 2019

The incidence of deep vein thrombosis (DVT) in the critically ill ranges from 3.6% to 37%. Despite seemingly adequate prophylaxis the risk for DVT is still between 4 and 15%.

Currently the known risk factors can be divided into inherited and acquired. In addition, the underlying disease and comorbidities play a major role, e.g., history of DVT, malignancy, ongoing infectious disease, cardiovascular disease and pregnancy.

DVT prevention is applied in various ways and timings. Principally, the choice is between mechanical, pharmacological and a combination of both.

Regarding the mechanical prophylaxis, recommendations point more to the use of intermittent pneumatic stockings (IPS), which are more effective with less side effects than simple stockings. Whenever pharmacological treatment carries a relatively high risk (e.g., fresh bleeding, traumatic brain injury) mechanical prevention might be started. However, it is still under debate whether the combination of IPS with pharmacological prophylaxis is superior.

Like all anticoagulant therapy, the risk (and consequences) of DVT should be balanced against the risk of bleeding. A variety of scoring systems, like the Well's score, the Caprini score and the Has-Bled score exist to group the risks. In terms of risk assessment, bleeding after peripheral surgery might be less dangerous than after intracranial surgery.

In general, low molecular weight heparins (LMWH) are preferred above unfractionated heparin (UFH). One reason might be the risk of heparin induced thrombocytopenia (HIT), which is higher with UFH than with LMWH. On the other hand, UFH have a shorter half-life necessitating at least two daily injections, while the LMWH schemes apply a once daily injection. However, the shorter half-life and the ease of reversal might be an argument for UFH use in patients at bleeding risk. In contrast, LMWH's carry a higher risk of bioaccumulation. The route of application seems to be another point of concern. In the critically ill, peripheral organ perfusion might be disturbed by the disease or the therapy (i.e. vasoconstriction or edema).

It is still a debate if oral anticoagulants should be used in critical care. Mainly concerns are raised from pharmacological considerations. For instance, if enteral feeding is only possible via tubes, grinding of tablets will change the galenic of the drugs and their bioavailability. In addition, it is not clear whether orally applied drugs will be resorbed completely. Excretion of drugs might be altered due to impairment of kidney and/or liver function which could result in their accumulation.

Finally, changes in the coagulation system due to the underlying disease might occur unexpectedly and therefore unanticipated.

In concert with difficulties in laboratory measurement and reversal of the drug benefits of oral anticoagulants do not outweigh risks and disadvantages. Therefore, it seems not recommendable to start any kind of oral anticoagulation before the patient's condition is stable enough which is mostly the moment of discharge from the ICU.
Social media and critical care
Authors: Yusaf Mamoon
Published: December 2019

Social media has transformed the way we communicate with each other in the last decade or so. Out of 4 billion internet users, more than 3 billion are on social media. The medical community has also been transformed in terms of how we approach this vast medium of information. Microblogging sites like Twitter are beneficial in the way we share and disseminate professional knowledge. The critical care community has recently gained a lot of pace on the social media platform and are showing their presence in numbers. Although use of social media in critical care has great potential to benefit its users, it comes with its own challenges. This includes inaccurate information and slow adaptation. So the question arises: How can the critical care community make the best use of social media resources while ensuring the right knowledge is shared and practiced, and patient confidentiality is always respected?

Twitter has been used as a medium to not only spread information but also as a platform to teach critical care physicians and nurses. There are elements which affect the usability, efficiency, effectiveness, and widespread acceptance of Twitter as a teaching aid. FOAM, free open access medical education, is an online movement taking place across social media, blogs, and podcasts that is challenging traditional methods of medical education. FOAM provides a free platform for learners to not only receive information but also share it with other users. It gives the learner a chance to tailor their resources according to their individual needs. In addition, learners can reach out for assistance from the source much more easily as compared to traditional ways. But concern has been raised on how to best approach these resources as they do not undergo vigorous checks like peer reviewed articles. Check and balance of the validity of the provided information is often left up to the learners discretion. It can leave educational gaps at times and may not be applicable worldwide. Similarly, declaration of conflict of interest is not mandatory on these platforms hence it is often impossible to identify commercial bias.

It can be quite difficult to keep track of all the continuing professional development hours spent on social media but new applications are being developed, which can help. While on social media, all the norms and etiquette of healthcare professionalism should be maintained such as patient confidentiality and appropriate interprofessional relationships. There are evolving tools to evaluate the quality of various resources like SMi (Social Media Index) and HONcode (Health on the Net Code of Conduct).

Social media, when used correctly, can be effective for self-directed learning, holding discussions with other critical care and healthcare professionals while reflecting on newly-acquired knowledge. Although the information must be used with due care, as the peer review is mostly inexistent in social media as people can post what they want, it is one of the most exciting and evolving areas in critical care practice.
Weird and wonderful ICU cases: Unusual causes of shock
Authors: Al-Busaidi Mujahid
Published: December 2019

During their practice, intensivists are ought to face challenging cases that are rare. Intensivists need to be aware of the rare causes of shock beyond common presentations. In each category of shock, there are rare causes that require prompt identification and management. Certain clues in the patient's presentation might point to those rare causes.

Classically shock is classified into: distributive, hypovolemic, cardiogenic, and obstructive. In this era of bedside point-of-care ultrasound, intensivists are able to promptly identify the cause of shock and institute a resuscitation plan. However, there are cases when the diagnosis is still obscure and the cause of shock is not easily identified. For example, in a study of patients admitted with presumed septic shock, 7.4% had no identified cause of shock and 11% had sepsis mimickers.

Hypovolemic shock occurs secondary to a reduction in the effective circulating volume secondary to fluid loss or third spacing. A rare cause of hypovolemic shock is idiopathic capillary leak syndrome (Clarkson Syndrome). The syndrome is characterized by recurrent episodes of rapidly progressive generalized edema, shock, renal failure and high hematocrit. The episode usually resolves in 3-7 days where the capillary leak resolves and a phase of pulmonary edema occurs. Several treatment options such as intravenous immunoglobulin (IVIG) and aminophylline were used in case reports.

Vasodilatory shock occurs secondary to peripheral vasodilation and decrease in blood flow. It occurs as part of the systemic inflammatory response syndrome for which sepsis, acute pancreatitis, acute liver failure, and major trauma are common causes. Rare causes that need to be considered include: hemophagocytic lymphohistiocytosis (HLH), systemic mastocytosis, and toxic shock syndrome.

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome characterized by macrophage activation and engulfment of hemopoetic cells which leads to pancytopenia. It is also characterized by cytokines storm that lead to a vasodilatory shock, multi-organ failure, and acute respiratory distress syndrome (ARDS). The most common triggers are infection, malignancy, and autoimmune diseases. Pointers to this diagnosis in the intensive care unit include: pancytopenias, hypofibrinogenemia, high triglycerides, and high ferritin. Treatment necessitates treating the underlying cause as well as using immune modifying therapies.

Systemic mastocytosis is a rare cause of recurrent anaphylaxis shock. It results from the accumulation of mast cells in tissues and can present with anaphylaxis and vascular collapse. An important clue to the diagnosis is the presence of urticarial pigmentosa and the absence of an allergen history.

Toxic shock syndrome is a unique cause of sepsis. It is caused by a pre-formed toxin produced by Staphylococcus aureus and Streptococcus pyrogenes. The clue to the diagnosis include the rapid onset after the precipitating factor, erythroderma, and skin desquamation. Treatment includes IVIG and Clindamycin.
Filosofia e Historia Natural em Bacon
Authors: Eva Luiz Antonio Alves
Published: December 2019

Este artigo examina a concepção de História Natural de Francis Bacon a partir de sua relação com literatura cética discutida no século XVI. Mais exatamente, procura mostrar que essa obra representa uma radicalização de uma tendência naturalista presente no tratamento cético da noção de “milagre”, tal como reconhecível no De Divinatione, de Cícero, e nos Ensaios de Montaigne, dentre outras obras.
Editorial
Authors: Zaterka Luciana
Published: December 2019

É com grande satisfação que apresentamos este número da revista Dois Pontos dedicado exclusivamente atemática da Filosofia e das Ciências nos séculos XVII e XVIII. Os vários artigos aqui publicados problematizam deum ponto de vista histórico e metafísico‑epistemológico uma ampla gama de questões relativas às diferentesciências do período, tais como história natural, física, química, matemática e ciências da vida.
Yvonne Rainer e os fins da dança: corpo, consciência e educação somática
Authors: Nicoliello Ana Rita
Published: December 2019

Neste artigo, articulo três sentidos distintos da expressão “Fins da Arte” - analítico-filosófico, estético e teleológico – para refletir acerca de um movimento importante no cenário da arte da dança, que transformou radicalmente o modo como nossa cultura ocidental compreende o corpo. Refiro-me à dança pós-moderna americana que se desenvolveu principalmente nas décadas de 60, 70 e 80, e tomo como paradigma o trabalho da coreógrafa, bailarina e cineasta Yvonne Rainer, denominado Trio A. Meu argumento é que, neste trabalho coreográfico, Yvonne Rainer coloca, com seu próprio corpo, a questão do “fim da dança” nos sentidos analítico-filosófico e estético, e como consequência promove uma reflexão sobre o “fim da dança” no sentido teleológico.
Consciência e justiça em Rousseau: dos tratados de casuística ao tribunal interior
Authors: Kawauche Thomaz
Published: December 2019

Este artigo sugere que a relação entre consciência e juízo no Emílio possa ser compreendida no âmbito dos debates filosóficos sobre moral e religião do final do século XVII. Mais especificamente, trata-se de situar aquilo que Rousseau designava por consciência no quadro teórico das discussões marcadas, de um lado, pelas transformações da ideia de justiça na história da casuística, e de outro, por um certo modelo antropológico que, na primeira metade do século XVIII, se coadunava com as necessidades teóricas das ciências emergentes.
O desafio da igualdade de género à luz da herança e das contradições de Rousseau
Authors: Nunes da Costa Marta
Published: December 2019

Rousseau é reconhecido como um dos grandes filósofos da nossa tradição ocidental, sobretudo pelo impacto que os seus ideais tiveram na definição da ideologia moderna de viés republicano e até mesmo liberal. Porém, apesar da defesa incansável daqueles que viriam a ser os ideais revolucionários franceses, Rousseau insiste em manter uma prática de desigualdade naturalizada, considerando as mulheres como inferiores e eternas desiguais dos homens. Mary Wollstonecraft foi a primeira a fazer a denúncia da contradição do pensamento de Rousseau, na obra que viria a ser o marco de uma literatura feminista: A Vindication for the Rights of Women. Porém, até mesmo esta denúncia está circunscrita àquele horizonte que Rousseau contribuira para desenhar: o horizonte da universalidade dos direitos, das liberdades e da igualdade. Neste artigo queremos caracterizar esta contradição levando em conta contribuições recentes de críticas feministas e apontando sua relação com o projeto democrático mais vasto.
Pensar a democracia em companhia de Rousseau e Tocqueville
Authors: Reis Helena Esser
Published: December 2019

Buscar nexos entre o pensamento de Rousseau e Tocqueville é facilitado porque o próprio Tocqueville afirma que Rousseau foi um dos autores que mais influenciou seu pensamento.   Influência, contudo, não significa concordância; e, ser um dos que mais o influenciou não significa uma única influência; razões que tornam nossa tarefa de buscar compreender os nexos entre um e outro mais instigante. Nosso esforço, neste artigo, recairá sobre a compreensão da concepção de democracia em cada um dos autores e, neste sentido, buscaremos evidenciar as características fundamentais que Rousseau, por um lado, e Tocqueville, por outro, atribuem à democracia. Em seguida, com base naquelas características apresentadas, investigaremos possíveis influências do pensamento rousseauísta sobre a concepção tocquevilleana, a fim de elucidar convergências e divergências entre os autores.
O pensamento político de Rousseau à luz do debate liberal-comunitário
Authors: Moscateli Renato
Published: December 2019

No debate entre liberais e comunitaristas, colocam-se perspectivas distintas sobre temas políticos cruciais, à medida que se busca definir a relação mais apropriada entre o indivíduo e a coletividade, ora salientando-se o valor da autonomia pessoal, ora enfatizando-se a importância da inserção identitária dos sujeitos no contexto social. Embora os escritos de Rousseau precedam a discussão entre essas correntes de pensamento, eles abrangeram temas sobre os quais as duas se debruçam. O autor toma o indivíduo como base para a construção do Estado, mas também mostra que essa unidade natural precisa ser transformada em uma parte de uma comunidade coesa e dotada de sua própria vontade geral. Assim, pretendo realizar um exercício interpretativo que, a partir de questões postas em relevo por aquele debate, analisará como Rousseau aliou seus princípios do direito político à preocupação com as particularidades de cada povo, o que faz suas teses transitarem entre as fronteiras do que, posteriormente, seriam os campos do liberalismo e do comunitarismo.
La importancia de la obra de G. Simondon para la filosofía contemporánea1
Authors: Rodríguez Pablo Esteban
Published: December 2019

The article puts G. Simondon’s work in perspective on three axes: its place within what A. Badiou called the“French philosophical moment” (1943-1991), the relationship between Simondonian concepts and some currents ofthought today and, finally, the way in which these notions are intertwined within the framework of the general theoryof individuation and the technics of the French philosopher. These three axes refer to the need to elaborate a philosophythat is contemporary with the questions posed by its time. According to our hypothesis, Simondon unfolded problemsforeign to his time (1924-1989), but very close to ours.Hence his importance for contemporary philosophy.Key‐words: politics; technics; science; humanism; individuation; transindividual.
Simondon e os sentidos da individuação biológica
Authors: Czeresnia Dina
Published: December 2019

Este texto destaca a importância do trabalho de Gilbert Simondon para se repensar a individualidadebiológica em uma nova base filosófica. Na constituição das ciências da vida, o caráter relacional dos processosbiológicos foi obscurecido por um deslocamento de sentidos, que ocorreu como um aspecto da construção maisampla da individualidade moderna no século XIX. Biólogos teóricos recuperam a importância da noção de relação,reivindicando uma nova concepção de interação biológica, assim como dos conceitos de organismo, adaptação,informação, evolução. O pensamento de Simondon vai ao encontro dessa perspectiva, propondo uma epistemologiaque afirma o caráter primordial da relação nos processos de individuação. Sua ontologia tem surpreendente afinidadecom a elaboração dessa vertente contemporânea da biologia teórica, sustentada por evidências empíricas da biologiamolecular. No entanto, elementos centrais da ontologia de Simondon, mesmo buscando dialogar com a ciência,situam-se em uma metafísica, abordando questões de fronteira nas ciências da vida e na relação entre ciência e filosofia.
Quem o cérebro pensa que é? ‐ uma neurologia das conectividades
Authors: Vilalta Lucas Paolo Sanches
Published: December 2019

Trata-se no presente texto de tomar o cérebro e alguns modelos da neurociência como pontos privilegiadosde análise para refletirmos sobre as conexões entre subjetivação e redes cognitivas e informacionais. Para tanto,realizamos uma neurologia crítica, a partir da filosofia simondoniana, de dois dos modelos hegemônicos decompreensão do cérebro, por um lado, o da substancialização do cérebro e das redes neurais como individualidadesjá constituídas, por outro, do cérebro como um sistema homólogo a uma máquina digital. Na sequência, propomos,a partir da filosofia da informação de Simondon, um modelo alternativo de compreensão do cérebro como umarede de redes em individuação. Por fim, propomos que tal compreensão alternativa nos permite reposicionar-nosem relação a algumas problemáticas epistemológicas e ético-políticas de nosso presente.