Internal Stratification Research Articles

Charge reversal in the collapse of polyelectrolyte star brushes under an electric field

We have performed Langevin dynamics simulations of the collapse of charged star brushes under an external electric field. It was found that the emergence of charge reversal of collapsed charged monomers on the grafting electrode is governed by the total net charge on a single grafted ordinary polyelectrolyte or polyampholyte chain. The mean value of the total net charge on a grafted star chain required to induce charge reversal on the grafting electrode decreases with increasing Bjerrum length. However, at very high Bjerrum length, the grafted star chains with ionizable functional groups are effectively neutral. Thus, the phenomenon of charge reversal becomes irrelevant at very high Bjerrum length. Simulation results revealed that the thickness of the adsorption layer is nearly independent of the average charge fraction, arm length and number of arms of grafted star chains as well as Bjerrum length. In the regime of charge reversal, simulation results showed that the degree of charge overcompensation increases with increasing charge fraction, but is nearly irrespective of the arm length and number of arms of grafted star chains. The degree of charge overcompensation was found to be a non-monotonic function of Bjerrum length and it reaches a maximum at an intermediate value of Bjerrum length. The effects of the characteristic parameters of grafted star chains and the applied electric field on the internal stratification of polyelectrolyte star brushes were also examined.

Проблемы внедрения обязательного внутреннего контроля и ревизии в организации на современном этапе

We considered the issues of the full-featured implementation of mandatory internal control and stratification audit, the activities of which are directly related to the globalization of the Russian economy, and to the improvement of the economic security of the enterprise as a whole. After all, growing crisis phenomena, the presence of a “gray” economic strategy and corruption manifestations can strangle any business, despite the level of integration in the region and its significance. In such circumstances, a revision of the classic internal control and audit continuity schemes are necessary. This will provide qualitative prerequisites to counteract challenges and threats at any level of enterprise economic stability with the possibility of leveling crisis phenomena, which, in turn, can actively affect the increase in jobs, employment in the region, collection of taxes and fees in general. We should note that the current geopolitical situation and the current legislative initiatives of the country's leadership qualitatively contribute to this, which, in turn, will lead to an increase in the quality of control and audit processes, including in budget spending. Increasing the investment attractiveness of the regions will be achievable only on the fact of consolidating the efforts of all authorities and local self-government with civil society institutions.

Physicians and management of emergency hospitals: professional power threatened?

Kanban is a technical arrangement for the organization of hospital care focused on the management of beds and clinical care, aimed at the quality and comprehensiveness of care and greater hospital bed turnover, and thus a reduction in length-of-stay and hospital costs. The system's most striking and innovative feature is constant, updated patient follow-up, shared by the professional team in systematic meetings. Characterize the probable impacts from the arrangement's adoption on physicians' professional power (autonomy and authority). Qualitative study in a municipal urgency-emergency hospital using the following data production techniques: ethnography of the hospital's routine, with observation and records in field diaries, and shared seminars with researchers and teams. Physicians value multi-professional work for qualifying their practice, as an ancillary and complementary line. Kanban tends to be controlled by "hybrids" (physicians who accumulate management and clinical functions) that express synergies between "clinical management" and "hospital bed management". Thus, in this arrangement interferences in physicians' work are not exercised from outside, and physicians' clinical decisions still condition the work of the other professional groups. Physicians do not see their authority and autonomy threatened by Kanban, given the linkage between management authority and professional authority. Still, aspects related to hybridization and internal stratification of the medical profession need to be better addressed in the debate on health professionals' power.

Spaces of Intercommunal Musical Relations in Ottoman Istanbul

The overall aim of this article has been to address those understated intermediary spaces that were produced in the context of musical interaction among the various communities residing in Istanbul in the Ottoman era. The underpinning theme in defining those spaces and tracing their dynamic trajectory throughout the history of the city has been the quest for voicing the diverse elements that composed them. This task has shown that the internal stratification of communities was often quite more multifaceted than previously thought and that the subsequent layers are not always easily traceable. As demonstrated, the internal diversity of communities was based both on the cultural and the social background of its members. Moreover, the makeup of each community and its musicians was constantly renewed through immigration. A consequent challenging question that needs to be addressed is whether and how this diversity was expressed in musical terms.

Afterwork and Overtime: The Social Reproduction of Human Capital

Afterwork and Overtime: The Social Reproduction of Human Capital

A black hole X-ray binary at ∼100 Hz: multiwavelength timing of MAXI J1820+070 with HiPERCAM and NICER

ABSTRACT We report on simultaneous sub-second optical and X-ray timing observations of the low-mass X-ray binary black hole candidate MAXI J1820+070. The bright 2018 outburst rise allowed simultaneous photometry in five optical bands (ugrizs) with HiPERCAM/GTC (Optical) at frame rates over 100 Hz, together with NICER/ISS observations (X-rays). Intense (factor of 2) red flaring activity in the optical is seen over a broad range of time-scales down to ∼10 ms. Cross-correlating the bands reveals a prominent anticorrelation on time-scales of ∼seconds, and a narrow sub-second correlation at a lag of ≈ +165 ms (optical lagging X-rays). This lag increases with optical wavelength, and is approximately constant over Fourier frequencies of ∼0.3–10 Hz. These features are consistent with an origin in the inner accretion flow and jet base within ∼5000 Gravitational radii. An additional ∼+5 s lag feature may be ascribable to disc reprocessing. MAXI J1820+070 is the third black hole transient to display a clear ∼0.1 s optical lag, which may be common feature in such objects. The sub-second lag variation with wavelength is novel, and may allow constraints on internal shock jet stratification models.

White-dwarf asteroseismology: An update

AbstractThe vast majority of stars that populate the Universe will end their evolution as white-dwarf stars. Applications of white dwarfs include cosmochronology, evolution of planetary systems, and also as laboratories to study non-standard physics and crystallization. In addition to the knowledge of their surface properties from spectroscopy combined with model atmospheres, the global pulsations that they exhibit during several phases of their evolution allow spying on the deep interior of these stars. Indeed, by means of asteroseismology, an approach based on the comparison between the observed pulsation periods of variable white dwarfs and the periods predicted by representative theoretical models, we can infer details of the internal chemical stratification, the total mass, and even the stellar rotation profile and strength of magnetic fields. In this article, we review the current state of the area, emphasizing the latest findings provided by space-mission data.

RIsk Stratification prior to lead Extraction and impact on major intraprocedural complications (RISE protocol).

An internal risk stratification algorithm was developed to decrease the risk of major adverse cardiac events (MACEs) during lead extractions (LEs). To report upon the impact of a risk stratification algorithm (RISE [RIsk Stratification prior to lead Extraction] protocol) on outcomes of LEs in a high-volume center. A retrospective review of a prospectively maintained LEs database was performed to identify features associated with MACEs. On the basis of the retrospective data, the RISE protocol differentiated LEs procedures into "High" and "Low" risk for occurrence of MACEs. High-risk LEs included dual-coil defibrillator lead (≥3 years), pacemaker and single-coil lead (≥5 years), and any StarFix coronary sinus lead. During the prospective evaluation of the RISE protocol, "High-risk" LEs were performed in an operating room (OR) or hybrid laboratory with the cardiac anesthesiologist, OR nursing team, perfusionist in the room, and a cardiac surgeon on the premises. "Low-risk" LEs were performed in the electrophysiology (EP) laboratory with anesthesia provided by EP nursing team. The preintervention (pre-RISE) and postintervention (post-RISE) group spanned 19 and 40 months and consisted of 449 (632 leads) and 751 patients (1055 leads), respectively. The primary outcome of MACEs in the two groups was compared. Protocol compliance was 100%. The primary outcome of MACEs occurred in 15 patients (3.34%) before and 12 (1.6%) after implementation of the RISE protocol (P = .04). RISE identified a low-risk group where minimal resources are needed and allowed for rapid intervention in the high-risk group that reduced the consequences of MACEs.

Pulsating white dwarfs: new insights

White dwarf stars constitute the final evolutionary stage for more than 95 per cent of all stars. The Galactic population of white dwarfs conveys a wealth of information about several fundamental issues and are of vital importance to study the structure, evolution and chemical enrichment of our Galaxy and its components ---including the star formation history of the Milky Way. In addition, white dwarfs are tracers of the evolution of planetary systems along several phases of stellar evolution. Also, white dwarfs are used as laboratories for astro-particle physics, being their interest focused on physics beyond the standard model. The last decade has witnessed a great progress in the study of white dwarfs. In particular, a wealth of information of these stars from different surveys has allowed us to make meaningful comparison of evolutionary models with observations. While some information like surface chemical composition, temperature and gravity of isolated white dwarfs can be inferred from spectroscopy, and the total mass and radius can be derived as well when they are in binaries, the internal structure of these compact stars can be unveiled only by means of asteroseismology, an approach based on the comparison between the observed pulsation periods of variable stars and the periods predicted by appropriate theoretical models. The asteroseismological techniques allow us to infer details of the internal chemical stratification, the total mass, and even the stellar rotation profile. In this review, we first revise the evolutionary channels currently accepted that lead to the formation of white-dwarf stars, and then, we give a detailed account of the different sub-types of pulsating white dwarfs known so far, emphasizing the recent observational and theoretical advancements in the study of these fascinating variable stars.

TORSIONAL WAVE SCATTERING IN TWO-LAYER PIPE WITH ACCOUNT FOR CONTACT RIGIDITY

The purpose of the paper is to study the wave propagation in a two-layer pipe, taking into account the rigidity of the contact between its layers. It is considered by solving the equation of motion for the vector and scalar potentials. A dispersion equation describing the frequency distribution of the phase velocities of waves in the waveguide under investigation is derived. In order to take into account the degree of contact rigidity between layers additional terms are added to the boundary conditions, including the normal (kGN) and tangential (kGT) contact rigidity coefficients. It is shown that torsional waves are separated from other types of waves and can be considered separately. The example of a numerical solution of the dispersion equation shows the possible behavior of dispersion curves without regard to the contact rigidity. The similar problem solution is provided with allowance for contact rigidity at various perforation coefficients. A conclusion is drawn on the effect of contact between layers on torsional wave behavior. The similar method solves the problem for a homogeneous pipe with internal stratification. Recommendations are given for taking into account the revealed regularities in the development of ultrasonic methods of control based on torsional wave propagation.

Modelling of dynamics and stratification effects in pellet boilers

Optimizing solar and pellet heating systems can be performed by system simulations in TRNSYS. However; this requires detailed boiler models that can properly model the thermal behaviour of the boilers, such as stratification and thermal response. This study uses a combination of existing models for modelling of the pellet burner part (TRNSYS Type 210) and the water volume (TRNSYS Type 340). This approach addresses the thermal dynamics and internal stratification more accurately than other available models. The objectives of this work are to develop a method for parameter identification for the model and to validate this method and the model itself. Sets of parameters are identified for two pellet boilers and one pellet stove with a water jacket (extended room heater) and the model is validated with a realistic dynamic operation sequence. The results show that modelling of stratification is essential in order to model the true behaviour of residential boilers. The test sequences used were adequate to parameterise the models and to provide the desired accuracy, except regarding the heat losses to room air. The model shows good accuracy for a stove and one boiler, but slightly worse performance for the other boiler regarding dynamics and modelling of the stratification.

Characterization and evaluation of permafrost thawing using GPR attributes in the Qinghai-Tibet Plateau

Recognizing the status of permafrost thawing and providing information for permafrost treatment in the Tibetan Plateau is a key problem. In this paper, a GPR experiment is designed to explore effective geophysical attributes for characterizing and evaluating the impact of key factors on permafrost thawing. A new algorithm for the assessment of rapid relative water content is also presented. After processing the GPR data, the weighted average frequency attribute, sweetness attribute and relative wave impedance attribute, which better characterize the effect of different factors on permafrost thawing, are selected. The weighted average frequency attribute can distinguish the thawing front and evaluate the extent of thawing in addition to the completely thawed fringe; the sweetness attribute can help to characterize thawing in water ice mixed with permafrost and evaluate the impact of free water on permafrost below the thawing front. The relative wave impedance attribute highlights the completely thawed fringe and other smaller internal stratifications in the permafrost thawing zone. Using the rapid relative water content assessment algorithm, it is easy to evaluate the extent of thawing using only GPR data. In addition, a thermokarst lake strengthens the degree of permafrost thawing. Permafrost thawing accelerates on sunny slopes. This study shows that roadbeds inhibit permafrost thawing and that a thermosyphon significantly inhibits permafrost thawing.

Effect of free surface on submerged stratified shear instabilities

In this paper, we have considered the effects of the shallowness of the domain as well as the air–water free surface on the stratified shear instabilities of the fluid underneath. First, we numerically solve the non-Boussinesq Taylor–Goldstein equation for smooth velocity and density profiles of a model shear layer with a free surface. When the depth of the fluid is relatively shallow compared to the shear layer thickness, the surface gravity waves existing at the free surface come closer to the waves existing in the shear layer. This can lead to resonant wave interactions, making the flow unstable to more varieties of modal instabilities. In order to obtain a deeper understanding of the instability mechanisms, we have performed analytical studies with broken-line profiles (profiles for which vorticity and density are piecewise constant). Furthermore, reduced-order broken-line profiles have also been developed, based on which dispersion diagrams are constructed. Through these diagrams we have underpinned the resonantly interacting waves leading to each type of instability. Two new instabilities have been found; one of them, referred to as the ‘surface gravity – interfacial gravity (SG-IG) mode’, arises due to the interaction between a surface gravity wave and an interfacial gravity wave, and would therefore be absent if there is no internal density stratification. The other one – the ‘surface gravity – lower vorticity (SG-LV) mode’, which arises due to the interaction between a surface gravity wave and the lower vorticity wave, surpasses Kelvin–Helmholtz (KH) instability to become the most unstable mode, provided the system is significantly shallow. Stability boundary of the SG-LV mode is found to be quite different from that of KH. In fact, KH becomes negligible for relatively shallow flows, while SG-LV’s growth rate is significant – comparable to the growth rate of KH for unbounded domains (${\approx}0.18$). Moreover, the SG-LV mode is found to be analogous to the barotropic mode observed in two-layer quiescent flows. We have found that the effect of a free surface on the Holmboe instability is not appreciable. Holmboe in the presence of a free surface is found to be analogous to the baroclinic mode observed in two-layer quiescent flows. Except for the Holmboe instability, remarkable differences are observed in all other instabilities occurring in shallow domains when the air–water interface is replaced by a rigid lid. We infer that the rigid-lid approximation is valid for large vertical domains and should be applied with caution otherwise. Furthermore, we have also shown that if shear is absent at the free surface, our problem can be modelled using Boussinesq approximation, that is, $O(1)$ density variations in the inertial terms can still be neglected.

A Locally Generated High‐Mode Nonlinear Internal Wave Detected on the Shelf of the Northern South China Sea From Marine Seismic Observations

AbstractIn this work, a secondary nonlinear internal wave (NIW) on the continental shelf of the northern South China Sea is investigated using high‐resolution seismic imaging and joint inversion of water structure properties combined with in situ hydrographic observations. It is an extraordinary wave combination with two mode‐2 NIWs and one elevated NIW occurring within a short distance of 2 km. The most energetic part of the NIW could be regarded as a mode‐2 NIW in the upper layer between 40 and 120 m depth. The vertical particle velocity of ∼41 cm/s may exceed the critical value of wave breaking and thus collapse the strong stratification followed by a series of processes including internal wave breaking, overturning, Kelvin‐Helmholtz instability, stratification splitting, and eventual restratification. Among these processes, the shear‐induced Kelvin‐Helmholtz instability is directly imaged using the seismic method for the first time. The stratification splitting and restratification show that the unstable stage lasts only for a few hours and spans several kilometers. It is a new observation that the elevated NIW could be generated in a deepwater region (as deep as ∼370 m). Different from the periodical NIWs originating from the Luzon Strait, this secondary NIW is most likely generated locally, at the continental shelf break during ebb tide.

Wind‐Eroded Crater Floors and Intercrater Plains, Terra Sabaea, Mars

AbstractAncient impact craters with wind‐eroded layering on their floors provide a record of resurfacing materials and processes on early Mars. In a 54 km Noachian crater in Terra Sabaea (20.2°S, 42.6°E), eolian deflation of a friable, dark‐toned layer up to tens of meters thick has exposed more resistant, underlying light‐toned material. These layers differ significantly from strata of similar tone described in other regions of Mars. The light‐toned material has no apparent internal stratification, and visible/near‐infrared spectral analysis suggests that it is rich in feldspar. Its origin is ambiguous, as we cannot confidently reject igneous, pyroclastic, or clastic alternatives. The overlying dark‐toned layer is probably a basaltic siltstone or sandstone that was emplaced mostly by wind, although its weak cementation and inverted fluvial paleochannels indicate some modification by water. Negative‐relief channels are not found on the crater floor, and fluvial erosion is otherwise weakly expressed in the study area. Small impacts onto this crater's floor have exposed deeper friable materials that appear to contain goethite. Bedrock outcrops on the crater walls are phyllosilicate bearing. The intercrater plains contain remnants of a post‐Noachian thin, widespread, likely eolian mantle with an indurated surface. Plains near Hellas‐concentric escarpments to the north are more consistent with volcanic resurfacing. A 48 km crater nearby contains similar dark‐over‐light outcrops but no paleochannels. Our findings indicate that dark‐over‐light stratigraphy has diverse origins across Mars and that some dark‐toned plains with mafic mineralogy are not of igneous origin.

Geological record of marine tsunami backwash: The role of the hydraulic jump

AbstractTsunamis are marked by distinct phases of uprush during coastal inundation and backwash when tsunami water recedes. Especially in the case of a steep coastal profile, the return flow may operate in a Froude‐supercritical regime, eroding the flooded area and transporting large volumes of sediment seawards. Important sediment accumulation occurs when the supercritical flow goes through a hydraulic jump where it becomes subcritical upon deceleration. An inferred example in coarse‐grained, mixed carbonates from the Lower Pleistocene on Rhodes (Greece) is described, with offshore bars up to 10 m long with scour‐and‐fill structures and steep antidune stratification. In finer‐grained sandy depositional systems such structures may be much longer, up to hundreds of metres. It is suggested here that, analogous to some turbidite beds, the apparent lack of structures or the presence of faint stratification that is common for graded sand layers within marine tsunamiites may in fact consist of extremely low‐angle, landward‐dipping backset‐strata that formed under a landward‐migrating hydraulic jump during the basinward retreat of tsunami water. Numerical simulations that focus on the internal stratification of backwash‐generated offshore bars support this hypothesis. The recognition of such deposits in the sedimentary record enlarges the toolbox for assessing the past frequency of tsunamis in coastal areas.

Large-scale bedforms induced by supercritical flows and wave–wave interference in the intertidal zone (Cap Ferret, France)

The Cap Ferret sand spit is situated along the wave-dominated, tidally modulated Atlantic coast of western France, characterized by a semidiurnal macrotidal range. It displays peculiar dome-like bedforms that can be observed at low tide across the intertidal zone. These bedforms exhibit a wavelength of ca. 1.2 m and an elevation of ca. 30 cm. They occur only when the incident wave heights reach 1.5–2 m. The internal stratifications are characterized by swaley-like, sub-planar, oblique-tangential, oblique-tabular, as well as hummocky-like stratifications. The tabular and tangential stratifications comprise prograding oblique sets (defined as foresets and backsets) that almost always show variations in their steepness. Downcutting into the bottomsets of the oblique-tangential stratifications is common. The sets of laminae observed in the bedforms share common characteristics with those formed by supercritical flows in flume experiments of earlier studies. These peculiar bedforms are observed at the surf–swash transition zone where the backwash flow reaches supercritical conditions. This type of flow can explain their internal architecture but not their general dome-like (three-dimensional) morphology. Wave–wave interference induced by the geomorphology (i.e. tidal channel) of the coastal environment is proposed as explanation for the localized formation of such bedforms. This study highlights that the combination of supercritical flows occurring in the surf–swash transition zone and wave–wave interferences can generate dome-like bedforms in intertidal zones.

Continuous Care Provided Through Comprehensive Medication Management in an Acute Care Practice Model.

Pharmacy practice models that foster pharmacists' accountability for medication-related outcomes are imperative for the profession. Comprehensive medication management (CMM) is an opportunity to advance patient care. The objective of this study was to evaluate the impact of a CMM practice model in the acute care setting on organizational, patient, and financial outcomes. Three adult service lines focused on at-risk patients identified using internal risk stratification methodology were implemented. Core CMM elements included medication reconciliation, differentiated clinical pharmacy services, inpatient MTM consultations, discharge services, and documentation. Mixed methods compared the effect of the CMM model before and after implementation. Historical patients served as comparative controls in an observational design. Pharmacists completed a 60-minute interview regarding their experiences. Qualitative data were analyzed using thematic coding to characterize perception of the model. Three pharmacists implemented the model on cardiology, hematology/oncology, and surgery transplant services and provided services to 75 patients during the study. A total of 145 medication-related problems were identified and resolved. CMM was associated with a nonsignificant reduction of 8.8% in 30-day hospital readmission rates ( P = 0.64) and a 24.9% reduction in 30-day hospital utilization ( P = 0.41) as well as a significant reduction of 86.5% in emergency department visits ( P = 0.02). Patients receiving discharge prescriptions from our outpatient pharmacies increased by 21.4%, resulting in an 11.3% increase in discharge prescription capture and additional revenue of $5780. Themes identified from qualitative interviews included CMM structure, challenges, value, and resources. This study demonstrated successful implementation of a CMM model that positively affected organizational, patient, and financial outcomes.

Structural, geochemical, and mineralogical investigation of active hydrothermal fluid discharges at Str\xfdtan hydrothermal chimney, Akureyri Bay, Eyjafj\xf6r\xf0ur region, Iceland

A submarine hydrothermal fluid discharge structure in Akureyri Bay, Eyjafjörður region, Iceland, was investigated by means of structural, geochemical, and mineralogical methods. Thermal and chemical gradients between the hydrothermal fluid and the subarctic seawater lead to an ongoing mineral precipitation. This process builds up hydrothermal chimneys of dozens of meters in height and they are still growing. The structural analysis reveals an internal stratification of the mineral precipitates at various scales from sub-micrometers to several decimeters. This stratification indicates random changes in the depositional system during the formation of the hydrothermal cones. Some mineral layers are characterized by a dominance of Si, Mg, and O. In contrast, others are dominated by Ca and O. However, the results of XRD analysis proved that the material consists mainly of a trioctahedral phyllosilicate of the smectite group, presumably saponite or stevensite. Additionally, aragonite and hisingerite could be present. The material is built up of numerous parallel tubes, which act as conductors in the hydrothermal chimneys. Consequently, a large amount of available pore space with pore volumes of up to 6 mm3 was detected in the sample by the porosity analysis.

Response of the North Atlantic surface and intermediate ocean structure to climate warming of MIS 11

Investigating past interglacial climates not only help to understand how the climate system operates in general, it also forms a vital basis for climate predictions. We reconstructed vertical stratification changes in temperature and salinity in the North Atlantic for a period some 400 ka ago (MIS11), an interglacial time analogue of a future climate. As inferred from a unique set of biogeochemical, geochemical, and faunal data, the internal upper ocean stratification across MIS 11 shows distinct depth-dependent dynamical changes related to vertical as well as lateral shifts in the upper Atlantic meridional circulation system. Importantly, transient cold events are recognized near the end of the long phase of postglacial warming at surface, subsurface, mid, and deeper water layers. These data demonstrate that MIS 11 coolings over the North Atlantic were initially triggered by freshwater input at the surface and expansion of cold polar waters into the Subpolar Gyre. The cooling signal was then transmitted downwards into mid-water depths. Since the cold events occurred after the main deglacial phase we suggest that their cause might be related to continuous melting of the Greenland ice sheet, a mechanism that might also be relevant for the present and upcoming climate.