Sudden Separation Research Articles

Females with a History of Spontaneous Coronary Artery Dissection Exhibit Greater Pressor Responses to Isometric Handgrip and Post-exercise Ischemia Compared to Healthy Females

Background: Spontaneous coronary artery dissection (SCAD) causes acute coronary syndrome via the sudden separation between the coronary arterial wall layers and/or hematoma. The SCAD patient population is >80% female who typically have few or no traditional cardiovascular disease risk factors (e.g., obesity, hypertension). Risk of a recurrent SCAD is reported as high as 19% at 3 years after an initial SCAD. Mechanisms underlying SCAD (re)occurrence are unknown. Common triggers for SCAD include sympathoexcitatory stimuli, including heavy exercise and intense Valsalva-like activities. This study tested the hypothesis that SCAD patients exhibit greater neurocardiovascular responses (e.g., blood pressure, heart rate, muscle sympathetic nerve activity) to isometric handgrip and post-exercise ischemia compared to healthy females. Methods: Eight females with a history of SCAD (age: 56±6 yrs, BMI: 28±4 kg/m2) and 6 age- and BMI-matched healthy female controls (CON, age: 55±8 yrs, BMI: 26±5 kg/m2) participated. Continuous blood pressure (finger photoplethysmography) and heart rate (3-lead ECG) were measured during rest (1 minute), isometric handgrip at 30% maximal voluntary contraction (2 minutes), and post-exercise ischemia at 220 mmHg (2 minutes) to isolate the skeletal muscle metaboreflex. Muscle sympathetic nerve activity (MSNA, peroneal microneurography) was measured in a subset of participants (5 SCAD/4 CON). Data are presented as an absolute change from rest (mean±SD). Two-way independent t-tests were used for statistical analyses. Results: Resting mean blood pressure (SCAD: 96±8 vs CON: 91±9 mmHg, p=0.354), heart rate (SCAD: 56±11 vs CON: 59±10 bpm, p=0.666), and MSNA (SCAD: 50±19 vs CON: 43±32 bursts/100 heartbeats, p=0.697) were not different between groups. Relative to healthy controls, SCAD patients elicited greater increases in mean blood pressure during isometric handgrip (SCAD: Δ9±3 vs CON: Δ4±4 mmHg, p=0.034) and post-exercise ischemia (SCAD: Δ7±4 vs CON: Δ3±3 mmHg, p=0.046). There were no group differences regarding heart rate responses during isometric handgrip (SCAD: Δ3±4 vs CON: Δ4±4 bpm, p=0.359) and post-exercise ischemia (SCAD: Δ3±4 vs CON: Δ2±3 bpm, p=0.861). Responses in MSNA during isometric handgrip (SCAD: Δ12±8 vs CON: Δ9±8 bursts/100 heartbeats, p=0.536) and post-exercise ischemia (SCAD: Δ11±2 vs CON: Δ13±10 bursts/100 heartbeats, p=0.713) also were not different between groups. Conclusion: These preliminary data suggest that compared to healthy females, female patients who experienced a SCAD exhibit greater pressor, but not chronotropic or sympathetic, responses to isometric handgrip and post-exercise ischemia. Exaggerated pressor responses to these perturbations may be a potential risk factor for SCAD (re)occurrence. NIH K23 HL155506, NIH T32 DK07352, NIH K01 HL148144, NIH UL1 TR0022377, and AHA 898649. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Picture books for young children of incarcerated parents: Through the lens of bibliotherapy

AbstractResearch suggests that bibliotherapy can help children cope with life's challenges through age‐appropriate reading and storytelling. Bibliotherapy has been employed to assist children in dealing with grief, divorce, adoption and other stressors. However, limited studies have investigated how this approach can support young children with incarcerated parents. Utilizing bibliotherapy as a framework, this study conducts a thematic analysis of children's picture books published between 1977 and 2014, featuring children of incarcerated parents as main characters to better understand the challenges they face. The study aims to explore the challenges depicted among child characters in picture books addressing parental incarceration for a young reading audience over almost 50 years. Our findings reveal that child characters grapple with various emotional, psychological and social challenges related to the sudden separation from their loved ones. We discuss the implications of each finding in greater detail.

Experimental investigation of the development of surfactant stabilized oil-water pipe flow downstream of a choke valve

In wells and multiphase flowlines the presence of valves, pumps and other complex geometries will considerable contribute to dispersion of the phases. In combination with the droplet stabilizing effect of natural surfactants contained in the crude oil and other production chemicals, this may lead to a considerable development length of the flow. Such effects should be understood and considered by future simulation tools. In the presented work, the described scenario was experimentally tested under controlled conditions. The development of dispersed oil-water flow downstream of a valve was monitored. Surfactant was added to the mineral oil to obtain a suitable droplet stability. The near horizontal test section was 220 m long and had an inner diameter of 109 mm. The vertical phase fraction distributions were measured at six locations along the pipe with traversing gamma densitometers. The test section was further instrumented with nine pressure transducers, four optical sections, and three droplet sampling points to monitor flow development. The flow development showed a characteristic behavior of a rather sudden separation after a certain length with stable dispersed flow conditions. The degree of inlet mixing and thus initial droplet size governed by the pressure drop over the mixing valve was found to be crucial for the development length. Flow rate and initial water fraction were of minor importance. The separation behavior was coalescence controlled as it would be expected for a surfactant stabilized system. Still, even if static separation bench tests resulted in very long separation time scales, the in-flow separation happened much faster. This indicates the importance of dynamic flow conditions and associated effects such as shear and a certain mixing to be preferential for the separation. The measured pressure drop of the dispersed flow was more than 20% higher than separated flow with otherwise the same conditions. As the flow separates, the pressure drop decreases and, as expected, finally approaches the value for separated flow. The work presents a detailed data set as basis for model development.

Weaning stress and intestinal health of piglets: A review.

Weaning is considered to be one of the most critical periods in pig production, which is related to the economic benefits of pig farms. However, in actual production, many piglets are often subjected to weaning stress due to the sudden separation from the sow, the changes in diet and living environment, and other social challenges. Weaning stress often causes changes in the morphology and function of the small intestine of piglets, disrupts digestion and absorption capacity, destroys intestinal barrier function, and ultimately leads to reduced feed intake, increased diarrhea rate, and growth retardation. Therefore, correctly understanding the effects of weaning stress on intestinal health have important guiding significance for nutritional regulation of intestinal injury caused by weaning stress. In this review, we mainly reviewed the effects of weaning stress on the intestinal health of piglets, from the aspects of intestinal development, and intestinal barrier function, thereby providing a theoretical basis for nutritional strategies to alleviate weaning stress in mammals in future studies.

Atomistic reaction mechanism of CVD grown MoS2 through MoO3 and H2S precursors

Chemical vapor deposition (CVD) through sulfidation of MoO3 is one of the most important synthesis techniques to obtain large-scale and high-quality two-dimensional (2D) MoS2. Recently, H2S precursor is being used in the CVD technique to synthesize 2D MoS2. Although several studies have been carried out to examine the mechanism of MoS2 growth in the presence of sulfur and MoO3 precursors, the growth of MoS2 in the presence of H2S precursor has largely remained unknown. In this study, we present a Reactive molecular dynamics (RMD) simulation to investigate the reaction mechanism of MoS2 from MoO3 and H2S precursors. The intermediate molecules formation, the reason behind those formations, and the surface compositions of MoOxSyHz during the initial steps of CVD have all been quantified. Surprisingly, a sudden separation of sulfur atoms from the surface was observed in the H2S precursor system due to the substantial oxygen evolution after 1660 K. The sulfur detachments and oxygen evolution from the surface were found to have a linear relationship. In addition, the intermediate molecules and surface bonds of MoS2 synthesized by MoO3 and H2S precursors were compared to those of a system using S2 and MoO3 precursors. The most stable subsidiary formation from the H2S precursor was found to be H2O, whereas in case of S2 precursor it was SO. These results provide a valuable insight in the formation of large-scale and high-quality 2D MoS2 by the CVD technique.

On black holes, psychic deadness and aliveness

ABSTRACT In this article, the author uses the astrophysical term of the ‘black hole’ to describe the subjective feelings of patients who have experienced trauma in their inter-personal relationships, such as sudden separation or adultery. Such experiences are actually breakdowns that occurred in the past, but were not fully experienced. The fall into a black hole represents a deep regressive state in which the patient encounters a psychic deadness that he or she has tried to avoid. Presencing and therapeutic passion on the side of the therapist can help them to survive and confront dissociated self-states. Recovery from a black hole experience relies on physical and psychic aliveness, which are facilitated by the analytic setting.

The Absurdity of Human Life in Sampar Novel by Albert Camus

Absurdity experienced by humans in various fields of life, including its representation in the field of literature. The representation of Absurdity in literary works, especially translation literature, is widely known and has even been used as teaching material for students. The absurd literature of the translation, especially Albert Camus' Sampar novel, the authors chose to study and reveal the absurdist approach. This novel has become a material for teaching literature in Indonesian universities, so the results of this study can be used as reference material for teaching. The problem in studying an absurd novel is whether the feeling of Absurdity is only felt by the individual or the community in which the event occurred. In the novel Sampar, a collective absurdity will be described, which has not been revealed in Albert Camus's novel studies. The qualitative research methods are used with content analysis seen from existentialism philosophy. The most prominent consequence felt by the Oran community was the closure of the city door so that the Oran people experienced a sudden separation from people they loved without preparation. Sampar itself is a representation of collective Absurdity. The existence of sampar itself is also bizarre, weird, and irrational. Albert Camus shows his thoughts about human existence more thoroughly than other novels, acknowledging solidarity, friendship, and togetherness. According to Albert Camus, the absurd existence of humans is experienced at both individual and collective levels. There is no room for rationality, values, and moral-religious beliefs. These values have been devastated by the plague of world war, the crime of humanity that brought people to fear and despair. In the Sampar novel, there are individual absurdities felt by the leaders and the collective Absurdity felt by the people of Oran as a sense of solidarity with fellow human beings. High student learning motivation will affect better learning achievement. An understanding of human history after World War II and its absurd conditions can attract students to study absurd literary works.

Giant epigastric hernia induced by the second stage of labor in an obese multigravida: A case report

Several acute undesired events can occur during the second stage of labor due to a significant increase in the intra-abdominal pressure associated with the process of expulsion of the fetus. Herniation of loops of the bowel due to sudden separation or tear in the rectus fascia in a woman without the previous abdominal surgery is a very rare occurrence. We report a case of intrapartum herniation of intra-peritoneal viscus through a large epigastric defect that occurred during the second stage of labor.

Stiffening offshore composite wind-blades bonding joints by carbon nanotubes reinforced resin – a new concept

ABSTRACT Offshore wind-blades with excessive lengths (>100 m) are critical parts because of monolithic bonding that is holding the two halves, which may lead to sudden separation of edges while wind-turbine is in service. Offshore wind generation maintenance teams are targeting zero-maintenance. As a matter of fact, in the event of initiating mechanical damage, top and bottom skins of a wind blade should hold together as long as possible to allow enough time for maintenance to take place. We suggest an innovative concept that is a two-step strategy which consists first in strengthening the bond joints with carbon-nanotubes (CNTs), that be followed by a stitching of the two bonded joints with a composite cord. It is worthwhile to note that CNT can either reinforce the two halves of wind-blades and/or be added in between the pre-pregs composite plies before curing, to enhance bonding stiffness. A Finite Element model is proposed where simulation takes into account parameters such as CNT-weight fraction, chirality and CNTs inclination versus mechanical loading. Higher stiffness of joints and higher delamination strength for composites, are expected out of the concept. This article is intended to be a preliminary numerical study that must be viewed as a proof of concept.

CONNECTION BEHAVIOR IN COMPOSITE PROFILED STEEL SHEET WITH FERROCEMENT (PSSF) SYSTEM

This paper concerns with the behavior of the connections in the composite Profiled Steel Sheet with Ferrocement (PSSF) systems. The PSSF panels is a light weight composite panel consists of a profiled steel sheet (PSS) and ferrocement panel connected together by either mechanical fasteners or by epoxy adhesive resin. Ten push-out specimens were tested. The veriables were the strength of morter and the volume friaction of wire mesh for ferrocement panels, and types of connection between the two components. The ultimate load, the load slip relationship, and modes of failure were recorded. The results showed that the specimens connected by using* bolts of 10 mm diameter can sustain load greater by 64% than those connected by using bolts of 5 mm diameter. The ultimate load was found not to be inflenced** when the strength of ferrocement is increased from 35 MPa to 45 MPa. Also the effect of volume fraction of wire mesh was observed to enhance slightly the ultimate load when the layers of wire meshs is increased from 2 to 3 layers. For the specimens made by connecting the ferrocement components to the PSS by adhesive epoxy layer, a rigid connection was obtained and sudden separation occurred between the ferrocement component and steel sheet after local buckling of PSS.

Dialogues and Tensions in the Eating Habits of Syrian Refugees Living in São Paulo, Brazil

ABSTRACTThis study investigates the processes of acculturation, interculturality and interactions in the eating habits of Syrian refugees who had a Syrian food venue in the city of São Paulo, Brazil. We conducted a qualitative study, with an ethnographical design, with ten participants, using semi-structured interviews and participant and non-participant observation. There were changes in the preparation of consumed and served food products. These changes were accompanied by tensions, connected to the acculturation strategies and intercultural relations. Even with these changes, consuming Syrian food allowed our participants to maintain connections with their original country, despite the sudden temporal and spatial separation.

The influence of pore pressure on fracture behaviour of Normal-Strength and High-Performance Concretes at high temperature

Explosive spalling consists in the sudden separation of concrete layers or pieces from the surface exposed to fire, due to (a) stress caused by thermal gradients and external loads and (b) pore pressure rise induced by water vaporization. As regards the material properties, the phenomenon is affected by some meso- and micro-structural aspects mainly concerning the interaction during heating among cement paste, aggregate and fibre, thus influencing porosity and permeability variation at high temperature. Focusing on the effect of pore pressure in fracture behaviour of Normal-Strength and High-Performance Concretes, an experimental campaign has been planned, aimed at investigating the role played by the mix design. Nine concrete mixes have been studied considering three grades (fc ≥ 40, 60 and 90 MPa), three aggregate types (silico-calcareous, basalt and calcareous aggregates) and different fibre types and contents (monofilament or fibrillated polypropylene fibres). The experimental study, based on indirect tension tests performed under different levels of sustained pore pressure, clearly shows that the influence of pressure on concrete fracture response during heating strongly depends on mix design.

Progressive habituation to separation alleviates the negative effects of weaning in the mother and foal

Early and definitive separation between offspring and their mothers has negative consequences on behavioral and physiological responses. This study compared sudden and definitive weaning (Sudd group, N = 16) and weaning involving progressive habituation to separation using a fence line during the month preceding definitive separation (Prog group, N = 18). The impact of these two methods was assessed in both foals and their mothers through behavioral and biological parameters, including salivary cortisol, telomere length and blood transcriptomes. On the day of definitive separation, Prog foals neighed and trotted less and presented lower cortisol levels than Sudd foals. The weaning type also acted on the foals’ personality development; Prog foals became more curious, less fearful and less gregarious than Sudd foals, and the effects remained visible for at least 3 months. In principal component analysis, the Sudd and Prog groups were well separated along a factor where fear, reactivity and gregariousness correlated with high cortisol levels, but curiosity was associated with an increased telomere length and higher expression of genes involved in mitochondrial functions. Progressive weaning was also beneficial in mares. Principal component analysis showed that most Sudd group mares had higher cortisol levels and displayed more alert postures, neighs and activity on the day of weaning, indicating higher stress levels, while Prog mares had profiles that were characterized by more time spent resting on the day of weaning and longer telomere lengths. In conclusion, this study shows that progressive habituation to separation alleviates the negative effect of definitive weaning on both the mother and her young compared to sudden separation.

The Processes of Sudden Separation of Children with Intellectual Disability from Their Mothers

The Processes of Sudden Separation of Children with Intellectual Disability from Their Mothers

METHODS FOR FSI MODELING OF SPACECRAFT PARACHUTE DYNAMICS AND COVER SEPARATION

Fluid–structure interaction (FSI) modeling of spacecraft parachutes involves a number of computational challenges beyond those encountered in a typical FSI problem. The stabilized space–time FSI (SSTFSI) technique serves as a robust and accurate core FSI method, and a number of special FSI methods address the computational challenges specific to spacecraft parachutes. Some spacecraft FSI problems involve even more specific computational challenges and require additional special methods. An example of that is the impulse ejection and parachute extraction of a protective cover used in a spacecraft. The computational challenges specific to this problem are related to the sudden changes in the parachute loads and sudden separation of the cover with very little initial clearance from the spacecraft. We describe the core and special FSI methods, and present the methods we use in FSI analysis of the parachute dynamics and cover separation, including the temporal NURBS representation in modeling the separation motion.

Nonlinear Model Reduction of von Kármán Plates Under Linearized Compressible Fluid Flow

Areduced ordermodel (ROM) of linearized compressiblefluidflowcoupledwith a vonKarmanplate is developed. SeparateROMs for both thefluid and structure are derived and are coupled through a solidwall boundary condition at the interface boundary. The structural ROM is formulated using the method of quadratic components, which postulates that the full kinematics of the plate can be represented using linear and quadratic terms. The fluidROM is constructed via a proper orthogonal decomposition method. Both ROMs are further reduced via a Galerkin discretization, and the coupled system is implicitly integrated in time. The coupled model is subsequently compared with previously validated models that used either a linearized plate model with the linearized compressible fluid model or a quasi-static fluidmodel with the vonKarman platemodel. The comparisons are conducted in high-Machnumber regimeswhere the comparison is admissible, and excellent agreement is found. Analysis of the resulting limit cycles shows two sets of discontinuities in the limit cycle amplitudes. These discontinuities have two salient features: a snap through phenomenon in phase space is observed in the higher modes, and the coalescing of several of the lower modes is observed below the critical dynamic pressures followed by a sudden separation above the critical dynamic pressures.

A Simplified Model for Explosion Venting Due to the Separation of a Heavy Protective Cover

The paper presents a study aiming at simulation and understanding of some characteristics of an interior explosion within a room with an opening, that is initially being closed by a heavy cover, and may open gradually due to the effect of the explosion products. An effective simplified model of explosion venting due to separation of the protective cover has been developed. The developed model with lumped parameters is based on the Bernoulli equation and describes the quasi-stationary phase of the vented interior explosion. The initial internal gas pressure induced by the very short non-stationary phase is predicted by the developed approximate analytical formula, based on the full energy conservation law. The formula yields very good agreement with experimental data and with numerical analysis results. The simulation of the unsteady outflow from a cylindrical high-pressure vessel upon a sudden separation of the cover has shown that the developed simplified model yields the integral characteristics of the outflow process (such as a maximum cover's velocity and displacement etc) with reasonable accuracy. The proposed approach is demonstrated by the simulation of gas outflow from a chamber upon a sudden separation of the cover or upon a rectangular shutter rotation about a fixed line hinge. The analysis has been performed using the developed simplified approach and through simulations with AUTODYN. A good correspondence between both methods has been obtained. The effect of gravity on the protective cover velocity and displacement has been also examined.

A simplified model with lumped parameters for explosion venting simulation

The paper presents a study aiming at simulation of some characteristics of an interior explosion within a room with an opening, that is initially closed by a heavy cover, and is gradually opened due to the pressures exerted by the explosion products. An effective simplified model of explosion venting due to separation of the protective cover has been developed. The developed model with lumped parameters is based on the Bernoulli equation and describes the quasi-stationary venting phase of the interior explosion. The initial internal gas pressure induced by the very short non-stationary phase is predicted by the developed approximate analytical formula, based on the full energy conservation law. The formula yields very good agreement with experimental data and with numerical analysis results. The simulation of the unsteady outflow from a cylindrical high-pressure vessel upon a sudden separation of the cover has shown that the developed simplified model yields the integral characteristics of the outflow process (such as a maximum cover’s velocity and displacement etc.) with reasonable accuracy. The proposed approach is demonstrated by the simulation of gas outflow from a chamber upon a sudden separation of the cover or upon a rectangular shutter rotation about a fixed line hinge. The analysis has been performed using the developed simplified approach and through simulations with AUTODYN. A good correspondence between both methods has been obtained. The effect of gravity on the protective cover velocity and displacement has been also examined.

Study of the load‐following performance of distributed generators in a micro‐grid

AbstractDistributed generators such as the micro‐turbine generator (MTG), fuel cell (FC) and solar power generator will be increasingly installed and operated in distribution networks. With this tendency, a new concept of energy supply system called the micro‐grid is now being studied and tested in the field today. This paper presents the results of a study on the load‐following performance of typical distributed generators, MTG and FC by modeling and simulations. In addition, behaviors of voltage and frequency in a micro‐grid after sudden separation from the utility grid (islanding condition), in which MTG and FC are installed, were studied by simulations. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Simulations on atomic-scale friction between self-assembled monolayers: Phononic energy dissipation

Atomic-scale friction between self-assembled monolayers (SAMs) on Au (1 1 1) has been studied through molecular dynamics simulations, with emphasis on the mechanism of energy dissipation. Results show that the shear stress and chain angle on commensurate SAMs exhibit a clean periodic pattern and atomic stick–slip friction, which manifests a gradual storage and sudden release of energy. Using a simple model of two atoms, analysis shows that the atomic stick–slip originates from the dynamic instability of molecule motion. Energy has been built up during the stick, followed by a sudden separation as the equilibrium becomes unstable, and most energy dissipates at the time of slip. Moreover, the simulations reveal that more energy is stored and released in commensurate sliding, resulting in much higher friction than that in incommensurate cases. The contradictory frictional behavior can be traced to the difference in the number and strength of the Van der Waals bonds, formed in the two types of contacts.