Complexity analysis of sleep and alterations with insomnia based on non-invasive techniques

For the first time, fractal analysis techniques are implemented to study the correlations present in sleep actigraphy for individuals suffering from acute insomnia with comparisons made against healthy subjects. Analysis was carried out for 21 healthy individuals with no diagnosed sleep disorders and 26 subjects diagnosed with acute insomnia during night-time hours. Detrended fluctuation analysis was applied in order to look for 1/f-fluctuations indicative of high complexity. The aim is to investigate whether complexity analysis can differentiate between people who sleep normally and people who suffer from acute insomnia. We hypothesize that the complexity will be higher in subjects who suffer from acute insomnia owing to increased night-time arousals. This hypothesis, although contrary to much of the literature surrounding complexity in physiology, was found to be correct—for our study. The complexity results for nearly all of the subjects fell within a 1/f-range, indicating the presence of underlying control mechanisms. The subjects with acute insomnia displayed significantly higher correlations, confirmed by significance testing—possibly a result of too much activity in the underlying regulatory systems. Moreover, we found a linear relationship between complexity and variability, both of which increased with the onset of insomnia. Complexity analysis is very promising and could prove to be a useful non-invasive identifier for people who suffer from sleep disorders such as insomnia.     

Fractal dimension of the grain boundary fracture in creep-fracture of cobalt-based heat resistant alloys

The effects of grain boundary configuration and creep conditions on the fractal dimension of the grain boundary fracture (D _f) were investigated using commercial cobalt-based heat resistant alloys, namely, HS-21 and L-605 alloys. Creep-rupture experiments were carried out under the initial creep stresses of 19.6–176 MPa in the temperature range from 1089–1422 K in air. The value of D _f was larger in specimens with serrated grain boundaries than in those with straight grain boundaries in the HS-21 alloy under the same creep condition, and the difference in the value of D _f between these specimens was large in the scale range of the analysis which was less than about one grain boundary length. However, there was almost no difference in the value of D _f between the specimens with serrated grain boundaries and those with straight grain boundaries in the L-605 alloy, because there was no obvious difference in the microstructure between these specimens. The value of D _f increased with decreasing creep stress in the scale range of the fractal analysis larger than about one grain boundary length in both HS-21 and L-605 alloys, while the stress dependence of D _f was larger in the HS-21 alloy. The stress dependence of D _f was explained by the stress dependence on the number of grain boundary microcracks linked to the fracture surface. The value of D _f estimated in the scale range smaller than about one grain boundary length showed essentially no stress dependence in both L-605 and HS-21 alloys.     

Determination of vortex friction in a rotating type ii superconductor with a self-compensating torsion balance

A torque method is described for investigating pinning and viscous friction of vortices in a type II superconductor which continuously rotates with frequency f in a magnetic field H directed perpendicular to the axis of rotation. A self-compensating torsion balance was developed to allow the torque D(H, f) to be measured for temperatures in the liquid helium range. The average flux density B(H, f) in the rotating specimen can also be determined. Data obtained from a niobium cylinder can be described by the linear relationship D(B, f) = D_o (B) + D'(B) f, where D_o and D' are determined by the dynamic pinning force and the viscous friction respectively.     

Fracture toughness and crack morphology in indentation fracture of brittle materials

The relationship between the indentation fracture toughness, K _c, and the fractal dimension of the crack, D, has been examined on the indentation-fractured specimens of SiC and AIN ceramics, a soda-lime glass and a WC-8%Co hard metal. A theoretical analysis of the crack morphology based on a fractal geometry model was then made to correlate the fractal dimension of the crack, D, with the fracture toughness, K _IC, in brittle materials. The fractal dimension of the indentation crack, D, was found to be in the range 1.024–1.145 in brittle materials in this study. The indentation fracture toughness, K _c, increased with increasing fractal dimension, D, of the crack in these materials. According to the present analysis, the fracture toughness, K _IC, can be expressed as the following function of the fractal dimension of the crack, D, such that $$In K_{IC} = {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}\{ In[2\Gamma E/(1 - \nu ^2 )] - (D - 1)In r_L \}$$ Where Γ is the work done in creating a unit crack surface, E is Young's modulus, v is Poisson's ratio, and r _L is r _min/r _max, the ratio of the lower limit, r _min, to the upper limit, r _max, of the scale length, r, between which the crack exhibits a fractal nature (r _min ?r?r _max). The experimental data (except for WC-8%Co hard metal) obtained in this study and by other investigators have been fitted to the above equation. The factors which affect the prediction of the value of K _IC from the above equation have been discussed.     

A Quantum Algorithm Detecting Concentrated Maps

We consider an arbitrary mapping f: {0, …, N − 1} → {0, …, N − 1} for N = 2ⁿ, n some number of quantum bits. Using N calls to a classical oracle evaluating f(x) and an N-bit memory, it is possible to determine whether f(x) is one-to-one. For some radian angle 0 ≤ θ ≤ π/2, we say f(x) is θ − concentrated if and only if e^2πif(x)/N ? e^{i[ψ₀?θ,ψ₀+θ]} for some given ψ₀ and any 0 ≤ x ≤ N − 1. We present a quantum algorithm that distinguishes a θ-concentrated f(x) from a one-to-one f(x) in O(1) calls to a quantum oracle function U_f with high probability. For 0 < θ < 0.3301 rad, the quantum algorithm outperforms random (classical) evaluation of the function testing for dispersed values (on average). Maximal outperformance occurs at θ=12sin−11π≈0.1620 rad.     

The possibility of using platinum foils with a rippled surface as diffraction gratings

The atomic structure and surface relief of thin cold-rolled platinum foils upon recrystallization annealing and loading under ultrahigh vacuum conditions have been studied by low energy electron diffraction (LEED), atomic force microscopy (AFM), and scanning tunneling microscopy (STM). The surface of samples upon high-temperature annealing and subsequent uniaxial extension of recrystallized Pt foils represents a fractal structure of unidirectional ripples on various spatial scales. The total fractal dimension of this surface is D _GW = 2.3, while the fractal dimensions along and across ripples are D _‖ ≈ 1 and D _⊥ ≈ 1.3, respectively. The optical spectra of a halogen lamp and a PRK-2 mercury lamp were recorded using these rippled Pt foils as reflection diffraction gratings. It is shown that Pt foils with this surface relief can be used as reflection diffraction gratings for electromagnetic radiation in a broad spectral range.     

Hydrothermal growth of beryl single crystals and morphology of their singular faces

The surface morphology of the best developed faces of emerald and red beryl single crystals grown from high-temperature hydrothermal solutions has been studied by atomic force microscopy. The results attest to dislocation-mediated layer-by-layer growth of the faces. Using experimentally determined growth front profiles, the fractal dimensions D _Fp and D _Fa of the faces are evaluated to be 1.1–1.4. These values indicate that the surfaces studied have a fractal character and can be investigated using elements of fractal theory.     

Fragmentation in oblique impaction for nanoparticle-agglomerates with different structures

Impact fragmentation can be used to disperse nanoparticle-agglomerates. While the fragmentation of openly structured (fractal dimension D_f?<?2) agglomerates during perpendicular impaction was the subject of several investigations, the fragmentation during oblique impaction is not experimentally investigated so far. During oblique impaction a tangential velocity component acts on the agglomerates leading to an increased fragmentation for the investigated agglomerate structures (with D_f?=?1.6, 1.8, 2.3, 2.6 and 3.0). For the agglomerates with D_f?=?1.6. 1.8, 2.3 and 2.6 the degree of fragmentation can be described with the Weibull-statistics using the tangential impact velocity. This shows that the fragmentation during oblique impaction is determined by the tangential velocity component. The reason for the differing behavior of spherical agglomerates could not be elucidated but it is hypothesized, that a transition from sliding to rolling during the impact occurs affecting the fragmentation behavior.The breakage pattern is obtained by analyzing the fragment size distribution as a function of the impact energy. For agglomerates with fractal dimensions of D_f?=?1.6, 1.8, 2.3 and 2.6 a broad size distribution is observed containing small clusters/primary particles, bigger fragments and intact agglomerates at low impact energies. Increasing the impact energy shifts the whole fragment size distribution to smaller sizes. A nearly total disintegration at high impact energies is reached. The spherical agglomerates fracture into nearly equal sized fragments resulting in a narrower size distribution, which is shifted to smaller sizes at higher impact energies.     

The anisotropic diffusion of water in Kevlar-epoxy composites

The diffusion of water into unidirectional Kevlar fibre reinforced epoxy resins was studied as a function of fibre orientation and, for unidirectional (0°) composites, as a function of volume fraction (V_f). As the angle increased from 0 to 90°, the diffusivity increased dramatically; i.e. as more and more fibre-ends were exposed to the shorter diffusion path, the diffusivity increased. The equilibrium weight gain of water (M) in the composites increased with theV _f of the fibre. M of Kevlar fibre was calculated to be 4.9%. At a constantV _f, specimens of the same thickness and width but different lengths were used to determineD ₂₂, the diffusion coefficient of the composite along the fibre, andD ₂₂, the diffusion coefficient transverse to the fibre. The initial data for the percentage weight gain against the square root of time were non-linear, which was attributed to the anisotropy of the diffusion process. The anisotropy arises from the much higher value ofD ₁₁ as compared toD ₂₂. AsV _f increased from 0.37 to 0.59,D ₁₁ increased from about 0.83 to about 4.2 × 10^–12m² sec^–1, whereasD ₂₂ decreased from 0.21 to 0.033 × 10^–12 m2 sec^–1. Thus, the ratioD ₁₁/D ₂₂ increased from 3 to over 100 as U increased. The experimental sorption data could be fitted satisfactorily with these diffusion coefficients.     

Rebound behavior of nanoparticle-agglomerates

In general, the rebound behavior of particles depends on the particle/substrate material combination and the particle size. In the present investigation the rebound behavior of nanoparticle agglomerates is investigated in a low pressure impactor and compared to single spherical particles. For agglomerates, their structure and mechanical strength will also affect the rebound behavior. The rebound of openly structured agglomerates (fractal dimension D_f < 2) is determined by the primary particle size and the particle-substrate combination. The impact velocity required for rebound (critical velocity) is independent of the agglomerate size and equal to the critical velocity of single spherical particles having the same size as the primary particles. In case of agglomerate fragmentation no rebound was observed for openly structured agglomerates. For denser agglomerates (D_f > 2), the critical impact velocity decreases with increasing agglomerate size, where the decrease is more accentuated for higher fractal dimensions, finally approaching the behavior of spheres.     

Estimating Bounds on Collisional Relaxation Rates of Spin-Polarized 87Rb Atoms at Ultracold Temperatures

We present quantum scattering calculations for the collisional relaxation rate coefficient of spin-polarized ⁸⁷Rb(f = 2,m = 2) atoms, which determines the loss rate of cold Rb atoms from a magnetic trap. Unlike the lighter alkali atoms, spin-polarized ⁸⁷Rb atoms can undergo dipolar relaxation due to both the normal spin-spin dipole interaction and a second-order spin-orbit interaction with distant electronic states of the dimer. We present ab initio calculations for the second-order spin-orbit terms for both Rb₂ and Cs₂. The corrections lead to a reduction in the relaxation rate for ⁸⁷Rb. Our primary concern is to analyze the sensitivity of the ⁸⁷Rb trap loss to the uncertainties in the ground state molecular potentials. Since the scattering length for the a³Σ⁺_u state is already known, the major uncertainties are associated with the X¹Σ⁺_g potential. After testing the effect of systematically modifying the short-range form of the molecular potentials over a reasonable range, and introducing our best estimate of the second-order spin-orbit interaction, we estimate that in the low temperature limit the rate coefficient for loss of Rb atoms from the f = 2,m = 2 state is between 0.4 × 10⁻¹⁵ cm³/s and 2.4 × 10⁻¹⁵ cm³/s (where this number counts two atoms lost per collision). In a pure condensate the rate coefficient would be reduced by 1/2.     

Homeostatic swimming of zooplankton upon crowding: the case of the copepod Centropages typicus

Crowding has a major impact on the dynamics of many material and biological systems, inducing effects as diverse as glassy dynamics and swarming. While this issue has been deeply investigated for a variety of living organisms, more research remains to be done on the effect of crowding on the behaviour of copepods, the most abundant metazoans on Earth. To this aim, we experimentally investigate the swimming behaviour, used as a dynamic proxy of animal adaptations, of males and females of the calanoid copepod Centropages typicus at different densities of individuals (10, 50 and 100 ind. l⁻¹) by performing three-dimensional single-organism tracking. We find that the C. typicus motion is surprisingly unaffected by crowding over the investigated density range. Indeed, the mean square displacements as a function of time always show a crossover from ballistic to Fickian regime, with poor variations of the diffusion constant on increasing the density. Close to the crossover, the displacement distributions display exponential tails with a nearly density-independent decay length. The trajectory fractal dimension, D_3D ≅ 1.5, and the recently proposed ‘ecological temperature’ also remain stable on increasing the individual density. This suggests that, at least over the range of animal densities used, crowding does not impact on the characteristics of C. typicus swimming motion, and that a homeostatic mechanism preserves the stability of its swimming performance.     

Pressure-Volume-Temperature Relations in Liquid and Solid Tritium

PVT relations in liquid and solid T₂ near the melting curve were measured over 20.5 K–22.1 K and 0 MPa–7 MPa (0 bar–70 bar) with a cell that used diaphragms for pressure and volume variation and measurement. Because of ortho-para self conversion, the melting pressure P_m and the liquid molar volume V_lm increased with time. The rates were consistent with a second order reaction similar to that for c the J = odd concentration: dc/dt = ?k₁c² + k₂c(1 ? c), where k₁ = 6−9×l0⁻²h⁻¹. By extrapolation, the ortho and para forms differed by ΔP_m~6 bar and ΔV_lm~0.5%. Measurements of the volume change on melting and the thermal expansion and compressibility for liquid T₂ were consistent with those for H₂ and D₂. Impurities such as H₂, HT, DT, and ³He were removed by a technique using an adsorption column of cold activated alumina. Corrections for ³He growth during an experiment were adequate except near the triple point.     

A magnetooptical study of the odd crystal field component in a terbium-yttrium aluminum garnet

We have studied the photoluminescence spectra and the luminescence magnetic circular polarization (LMCP) spectra in the region of the 4f-4f radiative transition ⁵D₄→⁷F₆ in the rare earth Tb³⁺ ion in a Y₃Al₅O₁₂ garnet matrix. A comparison of the experimental and theoretically calculated LMCP spectra allowed parameters of the odd crystal field component to be determined that removes the prohibition with respect to parity from the 4f-4f transitions in Tb³⁺ ion in the garnet structure. The energy spectra and wave functions of ⁵D₄ and ⁷F₆ multiplets of Tb³⁺ ion in a crystal field with the D₂ symmetry have been calculated.     

DEM study and machine learning model of particle percolation under vibration

This paper aims to understand model the effect of vibration on particle percolation. The percolation of small particles in a vibrated bed of big particles is studied by DEM. It is found the percolation velocity (V_p) decreases with increasing vibration amplitude (A) and frequency (f) when the size ratio of small to large particles (d/D) is smaller than the spontaneous percolation threshold of 0.154. Vibration can enable percolation when the size ratio is larger than 0.154, while V_p increases with increasing A and f first and then decreases. V_p can be correlated to the vibration velocity amplitude under a given size ratio. Previous radial dispersion model can still be applied while the dispersion coefficient is affected by vibration conditions and size ratio. Furthermore, a machine learning model is trained to predict V_p as a function of A, f and d/D, and is then used to obtain the percolation threshold size ratio as a function of vibration conditions.     

Transport Properties of Topological Insulator-Based Ferromagnet/f-Wave Superconductor Junction

We investigate effect of magnetically-induced relativistic mass and also anisotropic f-wave pair coupling on the tunneling conductance on the surface of a 3D topological insulator ferromagnet/superconductor junction, which two types of pairing for superconductivity are possible. A topological insulator as a new state of condensed-matter caused by spin–orbit interaction and time-reversal symmetry has a bulk band gap and gapless surface states. We use the BTK formalism to find the charge carriers behavior. Due to two different nature of order parameters of the f-wave superconductivity, the tunneling conductance is found to be linearly dependent on the magnetic gap in terms of f ₁ and the exponential for f ₂. It is shown that the conversion of the conductance peak from ZBCP to ZBCD occurs in the f ₁ case with increasing m, while this is not observed in f ₂. Also, we find that the conductance behaves as a unit step function for the superconductor electrostatic potential in f ₁, and this should be usable in nanoelectronic switch devices. In addition, we illustrate how the magnetic gap affects the transmission coefficient in quite different behaviors for order parameters.     

Identification of mass fractal in chemically synthesized ZnS quantum dots

Zinc sulphide quantum dots chemically capped with thioglycerol having two different sizes have been synthesized. The particles have a disordered sphalerite structure and are slightly contracted by 1% against the bulk. Small angle X-ray scattering investigations reveal that powders of these nanocrystallites are mass fractals that aggregate via a reaction-limited process to form irregular but rather dense networks with a fractal dimensionality of D _f = 2.7 and 2.1, respectively.     

On the formalization and reuse of scientific research

The reuse of scientific knowledge obtained from one investigation in another investigation is basic to the advance of science. Scientific investigations should therefore be recorded in ways that promote the reuse of the knowledge they generate. The use of logical formalisms to describe scientific knowledge has potential advantages in facilitating such reuse. Here, we propose a formal framework for using logical formalisms to promote reuse. We demonstrate the utility of this framework by using it in a worked example from biology: demonstrating cycles of investigation formalization [F] and reuse [R] to generate new knowledge. We first used logic to formally describe a Robot scientist investigation into yeast (Saccharomyces cerevisiae) functional genomics [f₁]. With Robot scientists, unlike human scientists, the production of comprehensive metadata about their investigations is a natural by-product of the way they work. We then demonstrated how this formalism enabled the reuse of the research in investigating yeast phenotypes [r₁ = R(f₁)]. This investigation found that the removal of non-essential enzymes generally resulted in enhanced growth. The phenotype investigation was then formally described using the same logical formalism as the functional genomics investigation [f₂ = F(r₁)]. We then demonstrated how this formalism enabled the reuse of the phenotype investigation to investigate yeast systems-biology modelling [r₂ = R(f₂)]. This investigation found that yeast flux-balance analysis models fail to predict the observed changes in growth. Finally, the systems biology investigation was formalized for reuse in future investigations [f₃ = F(r₂)]. These cycles of reuse are a model for the general reuse of scientific knowledge.     

Study on wood fracture parallel to the grains based on fractal geometry

The fracture toughness (K _IC ) parallel to the grains of five kinds of wood was tested by compact tension specimen and the profile contour analysis method was employed to measure fractal dimensions D _s of their fracture surfaces. The results show that fracture toughness parallel to the grains of various woods is different because of their textural diversity and such differences are also shown on the morphology of fracture surfaces. Furthermore, the fractal dimension D _s and fracture toughness ${K_{IC}^{TL} }$ parallel to the grains have evident direct proportional relation, and this helps to reveal the inherent relationship between fracture toughness of wood and its microstructure.     

Investigation of thermal conductivity and dielectric properties of LDPE-matrix composites filled with hybrid filler of hollow glass microspheres and nitride particles

The hybrid filler of hollow glass microspheres (HGM) and nitride particles was filled into low-density polyethylene (LDPE) matrix via powder mixing and then hot pressing technology to obtain the composites with higher thermal conductivity as well as lower dielectric constant (D_k) and loss (D_f). The effects of surface modification of nitride particles and HGMs as well as volume ratio between them on the thermal conductivity and dielectric properties at 1 MHz of the composites were first investigated. The results indicate that the surface modification of the filler has a beneficial effect on thermal conductivity and dielectric properties of the composites due to the good interfacial adhesion between the filler and matrix. An optimal volume ratio of nitride particles to HGMs of 1:1 is determined on the basis of overall performance of the composites. The thermal conductivity as well as dielectric properties at 1 MHz and microwave frequency of the composites made from surface-modified fillers with the optimal nitride to HGM volume ratio were investigated as a function of the total volume fraction of hybrid filler. It is found that the thermal conductivity increases with filler volume fraction, and it is mainly related to the type of nitride particle other than HGM. The D_k values at 1 MHz and microwave frequency show an increasing trend with filler volume fraction and depend largely on the types of both nitride particles and HGMs. The D_f values at 1 MHz or quality factor (Q × f) at microwave frequency show an increasing or decreasing trend with filler volume fraction and also depend on the types of both nitride particle and HGM. Finally, optimal type of HGM and nitride particles as well as corresponding thermal conductivity and dielectric properties is obtained. SEM observations show that the hybrid filler particles are agglomerated around the LDPE matrix particles, and within the agglomerates the smaller-sized nitride particles in the hybrid filler can easily form thermally conductive networks to make the composites with high thermal conductivity. At the same time, the increase of the value D_k of the composites is restricted due to the presence of HGMs.