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Dia, para- and ferromagnetism of rocks and minerals correspond to the wide range of magnetic susceptibility. Atomistic models of dia- and paramagnetism are considered. The Langevin function describes magnetic saturation of paramagnetic particles, whose magnetic susceptibility depends on temperature according to the Curie–Weiß law. Ferromagnetism, antiferromagnetism, ferrimagnetism and canted antiferromagnetism are considered. Ferromagnetic minerals are characterized by magnetic domains whose boundaries experience Barkhausen jumps during magnetization-demagnetization. Magnetic domains are separated by Bloch walls. Koenigsberg’s ratio, i.e. the ratio of induced and remanent magnetizations, depends on the shape demagnetization factor a The concept of locking temperature based on the magnetization relaxation time is used to reconstruct paleomagnetic fields, i.e. in the case of magnetic stripes of mid-oceanic ridge basalts. Principles of chemical, pressure and detrital-remanent magnetization. Focus Box 10.1: Magnetic field of a small dipole. Focus Box 10.2: Brillouin function. Focus Box 10.3: Electron shells, orbitals and orbital hybridization. Focus Box 10.4: Extended Weiss model.
Climate and weather have a great influence on the prevalence of depressive disorders. Selected physical parameters for instance light, temperature and pressure can be used to treat mood disorders.
The present mini-review aims at approximating the mechanisms by which selected, strictly controlled physical parameters in particular light, temperature, and oxygen pressure can help in the treatment of depression and determine their potential effectiveness.
Relevant literature was identified by searching the PubMed/Medline database, by combining the search strategy of free text terms and exploding a range of MESH headings relating to the topics.
Mechanisms that can modify the course of depression were briefly presented. Review of the literature showed the well-established position of bright light therapy (BLT) effective in treating seasonal (SAD) and non-seasonal affective disorders (non-SAD); safety and rapid-action of whole-body hyperthermia (WBH) and whole-body cryotherapy (WBC) were also demonstrated; the least data was available on hyperbaric oxygen therapy (HBOT), which had antidepressant properties only in people with concomitant neurological damages.
In addition to the well-established position of BLT in the treatment of depression, further research is needed on other methods, such as WBH, WBC, HBOT.
A constraint theory approach to creativity can conveniently be conceptualized in five different dimensions each of which captures some important way in which creativity is constrained. The five dimensions have been generated by the empirical patterns from comparing disciplines in the making. The first dimension is a list of the most important empirical types of constraints that emerge from theoretical sensitization of comparative data. All creative processes are constrained by physical constraints which was first noted by Hegel in his lectures on aesthetics and rediscovered be Elster. The important role of prototypes has been noticed by the art historian Ragnar Josephson and the literary theorist Johan Svedjedal. The role of knowledge constraints was noted by Randall Collins and elaborated by me. Rules of the game were discovered by Aristotle (theoretical, productive, practical knowledge) and rediscovered by Wittgenstein. Motivations have been at the core of sociopsychological and economic theories of creativity.
One of the main concerns about the fast spreading coronavirus disease 2019 (Covid-19) pandemic is how to intervene. We analysed severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) isolates data using the multifractal approach and found a rich in viral genome diversity, which could be one of the root causes of the fast Covid-19 pandemic and is strongly affected by pressure and health index of the hosts inhabited regions. The calculated mutation rate (mr) is observed to be maximum at a particular pressure, beyond which mr maintains diversity. Hurst exponent and fractal dimension are found to be optimal at a critical pressure (Pm), whereas, for P > Pm and P < Pm, we found rich genome diversity relating to complicated genome organisation and virulence of the virus. The values of these complexity measurement parameters are found to be increased linearly with health index values.
The decolonization, a process that leads to the nominal independence and international recognition of states, gained momentum in the late-1950s, having its peak in 1960, the African year, when 18 colonies, protectorates, and trust territories became independent. This chapter explores the decolonization of Africa from three perspectives: of the colonial powers, of the colonial states, i.e. the colonies themselves, and of the international system. It argues that there is not one explanation to capture the decolonization. Only if we scrutinize decolonisation from all three perspectives, we are able to comprehend that process in its complexity.
Coronavirus disease 2019 is an international pandemic. One of the cardinal features is acute respiratory distress syndrome, and proning has been identified as beneficial for a subset of patients. However, proning is associated with pressure-related side effects, including injury to the nose and face.
This paper describes a pressure-relieving technique using surgical scrub sponges. This technique was derived based on previous methods used in patients following rhinectomy.
The increased use of prone ventilation has resulted in a number of referrals to the ENT team with concerns regarding nasal pressure damage. The described technique, which is straightforward and uses readily available materials, has proven effective in relieving pressure in a small number of patients.
Chapter 3 is a general, rather short and partly descriptive introduction to general wave theory, without application of any differential equation. The emphasis is on mechanical waves, e.g., acoustic waves.
Chapter 4 introduces basic differential equations and boundary conditions for gravity waves propagating along a water surface. Assuming low wave amplitudes, equations are linearised. Then a quantitative discussion is given for harmonical (sinusoidal) waves propagating either on deep water, or otherwise on water of constant depth. Phase and group velocities are introduced, and then formulas are derived for the potential energy and the kinetic energy associated with a water wave. A closely related result is an important formula for the wave-power level, which equals the wave’s group velocity multiplied by the wave’s stored – kinetic + potential – energy per unit of sea surface. An additional subject is the wave’s momentum density. A section concerns real sea waves. Further, circular waves are mathematically described. Two sections of the chapter concern mathematical tools to be applied in Chapters 5–8 of the book. A final section considers water waves analysed in the time domain.
The first part of Chapter 7 deals with oscillating water columns (OWCs). The concepts of radiation conductance and susceptance are introduced. The former is related to the radiated power, whereas the latter represents the reactive power. Expressions for the power absorbed by the OWC are derived, which are analogous to those of the oscillating body WEC. The potential energy of the OWC is also discussed. The last part of Chapter 7 deals with wave energy converters that move in modes other than the six conventional rigid-body modes. The theory of generalised modes are described, and some examples are given to illustrate the utility of the theory.
Phase transitions are driven by pressure as well as temperature, and the use of pressure to tune the electronic structures of materials can help further our understanding of materials properties. Chapter 8 begins with basic considerations of the thermodynamics of materials under pressure, and how phase diagrams are altered by temperature and pressure together. Volume changes can also be driven by temperature through thermal expansion, and the concept of “thermal pressure” from nonharmonic phonons is explained. Electronic energy is responsible for big contributions of +PV to the free energy, and this chapter describes how electron energies are altered by pressure. Cross-terms between temperature and pressure are discussed. The chapter ends with a discussion of kinetic processes under pressure, and the concept of an activation volume.
The new edition of this popular textbook provides a fundamental approach to phase transformations and thermodynamics of materials. Explanations are emphasised at the level of atoms and electrons, and it comprehensively covers the classical topics from classical metallurgy to nanoscience and magnetic phase transitions. The book has three parts, covering the fundamentals of phase transformations, the origins of the Gibbs free energy, and the major phase transformations in materials science. A fourth part on advanced topics is available online. Much of the content from the first edition has been expanded, notably precipitation transformations in solids, heterogeneous nucleation, and energy, entropy and pressure. Three new chapters have been added to cover interactions within microstructures, surfaces, and solidification. Containing over 170 end-of-chapter problems, it is a valuable companion for graduate students and researchers in materials science, engineering, and applied physics.
Some authors advocate the use of a dedicated formula to predict the Fontan pressure starting from pre-Fontan catheterisation data. This paper aims at testing the predictive value of the mentioned formula through a retrospective clinical study.
Methods and Results:
Pre-Fontan catheterisation data and Fontan pressure measured at the completion were retrospectively collected. Pre-Fontan data were used to calculate the predicted pressure in the Fontan system. The predicted values were compared to the Fontan pressure measured at the Fontan completion and with the needs for fenestration. One hundred twenty-four Fontan patients were retrospectively enrolled (At Fontan: median age 30.73 [24.70–37.20] months, median weight 12.00 [10.98–14.15] kg). Fontan conduit was fenestrated in 78 patients. A poor correlation (r2 = 0.05128) between the measured and predicted data for non-fenestrated patients was observed. In the case of Fontan-predicted pressure <17.59 mmHg, the formula identified a good short-term clinical outcome with a sensitivity of 92%.
The proposed formula showed a poor capability in estimating the actual pressure into the Fontan system and in identifying patients needing fenestration. As the pressure into the Fontan system is determined by multiple factors, the tested formula could be an additional data in a multi-parametric approach.
To assess the effect of topical betahistine on Eustachian tube function in subjectively abnormal subjects in a hyperbaric chamber.
Active and passive Eustachian tube function was examined using tympanometry in a pressure chamber.
Active Eustachian tube function was tested against the negative middle ear pressure induced by increasing the chamber pressure to +3 kPa. One voluntary swallow decreased middle-ear pressure by a mean of 1.36 kPa. Passive Eustachian tube function was tested by measuring spontaneous Eustachian tube openings as the chamber pressure dropped from +10 kPa to ambient. Four distinct patterns of Eustachian tube behaviour were seen, three of which indicated Eustachian tube dysfunction. Betahistine had no positive effect on Eustachian tube opening, although previous animal studies had suggested a beneficial effect.
Topical betahistine had no effect on Eustachian tube function. Combining a hyperbaric chamber with tympanometry proved ideal for evaluating Eustachian tube function.
Thanks to the second law, entropy is the concept by wich the arrow of time can be expressed. Irreversibility is defined as internal production of heat. Work by compression of a gas is analysed for both reversible and irreversible processes, making obvious the difference between the internal pressure, which is the conjugate of the volume, and the external pressure associated with the force exerted on a piston. Chemical potentials are defined as the conjugate of the number of moles of substances contained in the system. Chemical reactions are readily seen as source of entropy production. Simple systems are defined, playing a role analogous to point masses in mechanics. Evolution of simple systems is worked out when they are subjected to heat and mechanical action.
As a new functional composite material, functionally graded shape memory alloy (FG-SMA) holds particular properties of both functionally graded materials and shape memory alloys. By bringing in a new concept of conical surface assumption, considering the axial deformation, a macroconstitutive model which can describe the thermal mechanical properties of a FG-SMA cylinder subjected to pressure and graded temperature loads is established in this work. Furthermore, a new layered finite element model (FEM) which can avoid the direct assumption of the macroproperties of the FG-SMA cylinder is provided. The theoretical results display a good agreement with the FEM results, which indicates that both the macroconstitutive model and the FEM provided here are valid. The obtained results show that the stress in the cylinder distributes complexly, and it decreases remarkably as a result of the martensite transformation. This research can provide a base for the design and in-depth investigation of FG-SMA materials.
The ground temperature down to 60 cm depth in western Dronning Maud Land (WDML), has been recorded since 2009. The study area is situated in a blockfield that comprises a shallow active layer above permafrost. Using ground thermal regimes and regional climate data, the temporal (seasonal and annual) variability of the active layer was characterized. Active layer depth was calculated for each site for five consecutive summers from 2009/10–2013/14, showing interannual variability with no overall trends of decreasing or increasing active layer depth. Particular attention was paid to 2010 as it matched the average for the ground thermal regimes over the six year study period, as well as the interpolation period used by Meteonorm®. Analysis showed significant synchronous relationships of ground thermal regimes with air temperature and incoming radiation. Moreover, a correlation between pressure and measured ground temperature during the transitional season of the Southern Annual Oscillation in May and September was identified.
Silicone Rubber (SR) filled with graphene nanoplatelets (GNPs) and carbon black (CB) is prepared for high performance flexible pressure sensor. Due to the synergetic effect of mixed GNPs and CB, the percolation threshold of GNPs/CB/SR is lower than that of CB/SR, which indicates the addition of GNPs is contributed to enhance the electrical conductivity of GNPs/CB/SR. Moreover, the GNPs/CB/SR has a higher electrical stability and weaker resistance creep than that of GNPs/SR. That is to say, the addition of CB can promote the electrical and mechanical performance of GNPs/CB/SR, simultaneously. The pressure sensor array based on GNPs/CB/SR with weight on different sensing element is tested, and the results show that the size of applied loading on the pressure-sensitivity array can be recognized accurately.
The concept of effective stress is one of the basic tenets of rock mechanics where the stress acting on a rock can be viewed as the total stress minus the pore water pressure. In many materials, including clay-rich rocks, this relationship has been seen to be imperfect and a coefficient (χ) is added to account for the mechanical properties of the clay matrix. Recent experimental results during the flow testing (both gas and water) of several rocks (Callovo-Oxfordian claystone, Opalinus Clay, Boom Clay) and geomaterials (bentonite, kaolinite) has given evidence for stable high pressure differentials. The design of the experiments allows multiple measurements of pore pressure, which commonly shows a complex distribution for several different experimental geometries. The observed stable high pressure differentials and heterogeneous pore pressure distribution makes the describing of stress states in terms of effective stress complex. Highly localized pore pressures can be sustained by argillaceous materials and concepts of evenly distributed pore pressures throughout the sample (i.e. conventional effective stress) do not fit many clay-rich rocks if the complexities observed on the micro-scale are not incorporated, especially when considering the case of gas flow.
Inner ear homeostasis is dependent on the vestibular aqueduct and its content, the endolymphatic duct. Narrow and enlarged vestibular aqueducts have both been associated with hearing loss in Ménière's and large vestibular aqueduct syndromes. This review investigated the correlation between vestibular aqueduct diameter and pure tone average, and the effect of measurement site (i.e. the midpoint or the external aperture).
Materials and methods:
A systematic review of the literature and meta-analysis of large case series published on the Allied and Complementary Medicine, British Nursing Index, Cumulative Index to Nursing and Allied Health, Embase, Health Business Elite, Health Management Information Consortium, Medline, PsycInfo and PubMed databases. References and personal books were also scrutinised.
A linear relationship between vestibular aqueduct diameter and hearing loss was observed, with a projected increase of 6 dBHL per unit of vestibular aqueduct diameter (95 per cent confidence interval, 2–10; p = 0.003). This relationship was independent of measurement site.
This dose-dependent or linear relationship supports the role of flow and/or pressure change as aetiological factors in the pathogenesis of hearing loss, as per Poiseuille's law. This aetiological association is strengthened by the fact that the observed relationship is independent of measurement site.