Covid-19 Case Statistics in Europe Show Moderate Negative Correlation with Vaccination Level

Based on the statistics of Covid-19 cases and vaccination level in the last quarter of 2021, a moderate negative correlation was detected between the level of vaccination and current and peak case numbers in a number of European health jurisdictions. Statistically significant correlation was detected after taking into account differences in the local phase of the cases curve, by comparing statistics at the similar phase such as near the top of a local wave rather than current. These results may indicate a certain level of effectiveness of vaccines in preventing Covid-19 spread in the population, though analysis of other factors is still needed for a confident conclusion.

Impurity effect on hysteric magnetoconductance: holographic approach

In this paper we study a hysteric phase transition from weak localization phase to hysteric magnetoconductance phase using gauge/gravity duality. This hysteric phase is triggered by a spontaneous magnetization related to ℤ2 symmetry and time reversal symmetry in a 2+1 dimensional system with momentum relaxation. We derive thermoelectric conductivity formulas describing non-hysteric and hysteric phases. At low temperatures, this magnetoconductance shows similar phase transitions of topological insulator surface states. We also obtain hysteresis curves of Seebeck coefficient and Nernst signal. It turns out that our impurity parameter changes magnetic properties of the dual system. This is justified by showing increasing susceptibility and the spontaneous magnetization with increasing impurity parameter.

Frequency Resolved Partial Discharges Based on Spectral Pulse Counting

A partial discharge (PD) classification methodology based counting PD pulses in the spectral domain is proposed and presented in this paper. The spectral counting data are processed using the proposed PD Spectral Pulse Counting Mapping technique (PD-SPCM), which leads to a Frequency-Resolved Partial Discharges (FRPD) map. The proposed map is then used for PD detection and classification. In this work, corona and slot FRPDs are presented in frequency bands up to 500 MHz, obtained from laboratory measurements performed using two hydro-generator stator bars. The electromagnetic signals from the PDs were captured using a patch antenna designed for this purpose and a spectral analyzer. The corona and slot PDs were chosen because one can be mistakenly classified as the other because they may present similar Phase Resolved PD (PRPD) maps and may occupy shared spectral bands. Furthermore, corona and slot PDs can occur concurrently. The obtained results show that the corona and slot PDs can be properly identified using the developed methodology, even when they occur simultaneously. This is possible because, as it is experimentally demonstrated, corona and slot PDs have appreciable levels of spectral pulse counting in particular bands of the frequency spectrum.

Additively Manufactured Zirconia for Dental Applications

We aimed to assess the crystallography, microstructure and flexural strength of zirconia-based ceramics made by stereolithography (SLA). Two additively manufactured 3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP: LithaCon 3Y 230, Lithoz; 3D Mix zirconia, 3DCeram Sinto) and one alumina-toughened zirconia (ATZ: 3D Mix ATZ, 3DCeram Sinto) were compared to subtractively manufactured 3Y-TZP (control: LAVA Plus, 3M Oral Care). Crystallographic analysis was conducted by X-ray diffraction. Top surfaces and cross-sections of the subsurface microstructure were characterized using scanning electron microscopy (SEM). Biaxial flexural strength was statistically compared using Weibull analysis. The additively and subtractively manufactured zirconia grades revealed a similar phase composition. The residual porosity of the SLA 3Y-TZPs and ATZ was comparable to that of subtractively manufactured 3Y-TZP. Weibull analysis revealed that the additively manufactured LithaCon 3Y 230 (Lithoz) had a significantly lower biaxial flexural strength than 3D Mix ATZ (3D Ceram Sinto). The biaxial flexural strength of the subtractively manufactured LAVA Plus (3M Oral Care) was in between those of the additively manufactured 3Y-TZPs, with the additively manufactured ATZ significantly outperforming the subtractively manufactured 3Y-TZP. Additively manufactured 3Y-TZP showed comparable crystallography, microstructure and flexural strength as the subtractively manufactured zirconia, thus potentially being a good option for dental implants.

Harmonic fluctuations in the relative paleointensity data?

<p>The existing relative paleointensity (RPI) database allowed the construction of reliable stacking curves for at least the last 1 Myr. Observed fluctuations in the RPI curves suggest both lithologic/climatic influence or geodynamo processes. Stacked power spectra for RPI data from ten North and South Atlantic cores revealed a spectral peak at ~5.3kyr for data covering the last 100 kyr. This signal exhibits a similar phase for most of the series. The observed spectral peak has no apparent correspondence in the benthic O<sup>18</sup> spectra from the same cores, suggesting the RPI signal is free from the climatic influence. Therefore, it may be a real geodynamo feature.</p>

A theory of Spring Persistence Barrier on ENSO. Part I: The role of ENSO period

In this paper, we investigate the role of El Niño-Southern Oscillation (ENSO) period in the spring persistence barrier (SPB) mainly using the neutral recharge oscillator (NRO) model both analytically and numerically. It is suggested that a shorter ENSO period strengthens the SPB. Moreover, in contrast to the strict phase locking of the SPB in the Langevin equation, the phase of a SPB is no longer locked exactly to a particular time of the calendar year in the NRO model. Instead, the phases of the SPB for different initial months shift earlier with the maximum persistence decline lag months. In particular, the phase of a SPB will be shifted from the early summer to early spring, corresponding to the initial months of the early half year and later half year. This feature demonstrates that for later half year, ENSO predictability decreases as the presence of ENSO period. For realistic parameters, the range of the phase change is modest, smaller than 2-3 months. Similar phase shift is also identified for the SPB in the damped ENSO regime, unstable ENSO regime and observation. Our theory provides a null hypothesis for the role of ENSO period in SPB.

Local Coupling and Conversion of Surface Waves due to Earth’s Rotation. Part 2: Numerical Examples

Summary Rotation of the Earth affects the propagation of seismic waves. The global coupling of spheroidal and toroidal modes by the Coriolis force over time is described by normal-mode theory. The local action of the Coriolis force on the propagation of surface waves can be described by coefficients for the coupling between propagating Rayleigh and Love waves as derived by (Landau & Lifshitz 1959). Using global wavefield simulations we show how the Coriolis force leads to coupling and conversion between both surface wave types depending on latitude, propagation direction, frequency, and local velocity structure. Surface wave coupling is most efficient for periods where the modes have similar phase velocities, a condition that is equivalent to the selection rules of the angular degree in the normal-mode framework, a phenomenon that we refer to as resonant coupling. In the time-domain, resonant coupling gradually converts energy from one wave type–Rayleigh waves or Love wave–into the other, which then propagates independently. Due to the lateral heterogeneity, the condition of equal phase velocity renders the rotational coupling location-dependent. East-west oriented ray path segments and segments at high latitudes (across the Poles) only weakly couple the fundamental mode Rayleigh and Love waves while coupling is strongest for propagation along the meridians across the equator. At 250 s period, where Love and Rayleigh waves have similar phase velocities, the net energy transfer from Rayleigh to Love wave reaches about 10% for one orbit.

Ontogeny and Anatomy of the Dimorphic Pitchers of Nepenthes rafflesiana Jack

An enigmatic feature of tropical pitcher plants belonging to the genus Nepenthes is their dimorphic prey-capturing pitfall traps. In many species, the conspicuously shaped upper and lower pitchers grow from a swollen leaf tendril tip until finally opening as insect-alluring devices. Few have studied the ontogeny of these traps from an anatomical and quantitative morphological perspective. We investigated whether the anatomy and development of lower and upper type pitchers of N. rafflesiana differ or overlap in terms of 3D geometric morphology and microstructure progression and presence. We hypothesized that there is an overlap in the initial, but not all, developmental stages of the two pitcher types and that one pitcher type is suspended in development. We identified four important morphological changes of pitcher ontogeny and defined these as curvation, elongation, inflation and maturation phases. Pitcher length indicated progress through developmental phases, and we propose to use it as a tool for indication of developmental stage. Microstructure development coincided with the developmental phases defined. Additionally, we discovered a new anatomical feature of extrafloral nectariferous peristomal glands between the inner peristome ridges of upper and lower pitchers being hollow and analyze the chemistry of the sugars on the outside of these glands. Ontogenetic shape analysis indicated that upper and lower pitcher types develop with similar phase progression but have no directly overlapping morphology. This means that upper pitchers are not a derived state from lower pitchers. Independent developmental programs evolved to produce distinctly shaped upper and lower pitchers in Nepenthes, likely to exploit different food sources.

Effect of Hatch Angle Rotation on the Thermal and Mechanical Properties of Micro Selective Laser Melted NiTi Shape Memory Alloy

NiTi shape memory alloy (SMA) has been widely used for bio-medical and aerospace applications due to its unique properties, i.e. shape memory effect and pseudoelasticity. However, the high ductility and work-hardening effect of NiTi lead to poor machinability. Additive manufacturing (AM), with excellent capability of fabricating complicated structures, has been used to fabricate NiTi components. To meet the increasing demand of product miniaturization, micro selective laser melting (μSLM) system equipped with finer laser beam has been developed to improve manufacturing resolution. This work studies the fabrication of NiTi SMA parts by μSLM for the first time. The effect of hatch angle rotation on the thermal and mechanical behaviors of μSLMed NiTi is analyzed. Columnar grains accompanied with equiaxed grains are observed in μSLMed NiTi. Laser rotation angles of 45/60/90° lead to weak crystallographic texture. Ti-rich secondary phases including Ti2Ni/Ti4Ni2Ox and TiC1-xNx are detected in the raw NiTi powder and the as-printed NiTi parts, respectively. The as-printed parts under different hatch angles show similar phase constitution. The thermal-induced transformation behavior was depressed with absence of transformation peak. The variation of hatch angle cannot activate the transformation peak. Varying hatch angle from 45° to 90°, the compressive strength and ductility reduce, and the hardness increases. The depressed thermal-/stress-induced phase transformation of the μSLM NiTi can be attributed to the Ti-rich secondary phases, which cause variation of matrix Ni/Ti ratio and inhomogeneous microstructure.

On phase transition behaviors of Kerr–Sen black hole

We investigate phase transitions and critical behaviors of the Kerr–Sen black hole in four dimensions. Computing the involved thermodynamical quantities including the specific heat and using the Ehrenfest scheme, we show that such a black hole undergoes a second-order phase transition. Adopting a new metric form derived from the Gibss free energy scaled by a conformal factor associated with extremal solutions, we calculate the geothermodynamical scalar curvature recovering similar phase transitions. Then, we obtain the scaling laws and the critical exponents, matching perfectly with mean field theory.