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We study the three-dimensional hydrodynamic interaction of a pair of identical, initially spherical capsules freely suspended in a simple shear flow under Stokes flow conditions. The capsules are filled with a Newtonian liquid (same density and viscosity as the suspending fluid). Their membranes satisfy the neo-Hookean constitutive law. We consider the rarely studied case where the capsule centres are initially located in (or near) the plane defined by the flow direction and the vorticity vector, i.e. in two different shear planes. The motion and deformation of the capsules are modelled by means of a boundary integral technique to compute the flows, coupled to a finite element method to calculate the force exerted by the membranes on the fluids. We follow the motion and deformation of the capsules as they are convected towards each other after a sudden start of the flow. Our main finding is that, depending on their initial position and deformability, the two capsules may oscillate slowly about the flow gradient axis, get nearer to each other at each oscillation to finally interact strongly and separate. This minuet motion had not been identified previously. We identify the regions of space where either simple crossing or minuet occurs. This phenomenon has a marked influence on the irreversible trajectory drift of two capsules after crossing: the minuet process leads to a significant trajectory displacement along the flow gradient when none was expected, based on the previous studies where the two capsules had a significant relative velocity.
As an important dimensionless parameter for the vortex formation process, the general form of the formation time defined by Dabiri (Annu. Rev. Fluid Mech., vol. 41, 2009, pp. 17–33) is refined so as to provide better normalization for various vortex generator configurations. Our proposed definition utilizes the total circulation over the entire flow domain rather than that of the forming vortex ring alone. It adopts an integral form by considering the instantaneous infinitesimal increment in the formation time so that the effect of temporally varying properties of the flow configuration can be accounted for properly. By including the effect of buoyancy, the specific form of the general formation time for the starting forced plumes with negative and positive buoyancy is derived. A theoretical prediction based on the Kelvin–Benjamin variational principle shows that the general formation time manifests the invariance of the critical time scale, i.e. the formation number, under the influence of a source–ambient density difference. It demonstrates that the general formation time, based on the circulation production over the entire flow field, could take into account the effect of various vorticity production mechanisms, such as from a flux term or in a baroclinic fluid, on the critical formation number. The proposed definition may, therefore, serve as a guideline for deriving the specific form of the formation time in other types of starting/pulsatile flows.
Seasonal influenza virus epidemics have a major impact on healthcare systems. Data on population susceptibility to emerging influenza virus strains during the interepidemic period can guide planning for resource allocation of an upcoming influenza season. This study sought to assess the population susceptibility to representative emerging influenza virus strains collected during the interepidemic period. The microneutralisation antibody titers (MN titers) of a human serum panel against representative emerging influenza strains collected during the interepidemic period before the 2018/2019 winter influenza season (H1N1-inter and H3N2-inter) were compared with those against influenza strains representative of previous epidemics (H1N1-pre and H3N2-pre). A multifaceted approach, incorporating both genetic and antigenic data, was used in selecting these representative influenza virus strains for the MN assay. A significantly higher proportion of individuals had a ⩾four-fold reduction in MN titers between H1N1-inter and H1N1-pre than that between H3N2-inter and H3N2-pre (28.5% (127/445) vs. 4.9% (22/445), P < 0.001). The geometric mean titer (GMT) of H1N1-inter was significantly lower than that of H1N1-pre (381 (95% CI 339–428) vs. 713 (95% CI 641–792), P < 0.001), while there was no significant difference in the GMT between H3N2-inter and H3N2-pre. Since A(H1N1) predominated the 2018–2019 winter influenza epidemic, our results corroborated the epidemic subtype.
The association between schizophrenia and decreased vitamin D levels is well documented. Low maternal and postnatal vitamin D levels suggest a possible etiological mechanism. Alternatively, vitamin D deficiency in patients with schizophrenia is presumably (also) the result of disease-related factors or demographic risk factors such as urbanicity.
In a study population of 347 patients with psychotic disorder and 282 controls, group differences in vitamin D concentration were examined. Within the patient group, associations between vitamin D, symptom levels and clinical variables were analyzed. Group × urbanicity interactions in the model of vitamin D concentration were examined. Both current urbanicity and urbanicity at birth were assessed.
Vitamin D concentrations were significantly lower in patients (B = −8.05; 95% confidence interval (CI) −13.68 to −2.42; p = 0.005). In patients, higher vitamin D concentration was associated with lower positive (B = −0.02; 95% CI −0.04 to 0.00; p = 0.049) and negative symptom levels (B = −0.03; 95% CI −0.05 to −0.01; p = 0.008). Group differences were moderated by urbanicity at birth (χ2 = 6.76 and p = 0.001), but not by current urbanicity (χ2 = 1.50 and p = 0.224). Urbanicity at birth was negatively associated with vitamin D concentration in patients (B = −5.11; 95% CI −9.41 to −0.81; p = 0.020), but not in controls (B = 0.72; 95% CI −4.02 to 5.46; p = 0.765).
Lower vitamin D levels in patients with psychotic disorder may in part reflect the effect of psychosis risk mediated by early environmental adversity. The data also suggest that lower vitamin D and psychopathology may be related through direct or indirect mechanisms.
The oriental armyworm, Mythimna separata is an important crop pest in eastern Asia. Nocturnal insects, including nocturnal moths, have phototactic behavior to an artificial light source. Phototactic behavior in insects is species-specific in response to different wavelengths of light sources. Our previous study showed that green (520 nm) light emitting diode (LED) light resulted in a significantly higher phototactic behavior in M. separata moths compared to the other wavelength LED lights. The goal of the present study is to investigate the influence of green light illumination on biological characteristics of different developmental stages in M. separata. Our results revealed that when different developmental stages of M. separata were exposed to the green light illumination in a dark period, several biological characteristics in all developmental stages except for egg stage were positively changed, but those of F1 generation M. separata which are next generation of the adults exposed to the green light did not significantly change compared with the control level. These findings suggest that green light illumination at night (or dark period) has a positive effect on the development and longevity of M. separata.
Maternal effects on offspring seeds are mainly caused by seed position on, and the abiotic environment of, the mother plant. Seed heteromorphism, a special form of position effect, is the production by an individual plant of morphologically distinct seed types, usually with different ecological behaviours. Seed heteromorphism is assumed to be a form of bet hedging and provides an ideal biological model to test theoretical predictions. Most studies of maternal effects on seeds have focused on abiotic environmental factors and changes in mean seed traits of offspring. Suaeda salsa is an annual halophyte that produces dimorphic seeds within the same inflorescence. We tested the hypothesis that plants grown from brown seeds of S. salsa have a higher offspring brown seed:black seed morph ratio and variance in seed size than plants from black seeds. Results from a pot experiment showed that plants grown from brown seeds had a higher brown seed:black seed ratio than plants grown from black seeds. This is the first layer of dynamic bet hedging. Brown seeds had higher size variation than black seeds, and seeds produced by plants from brown seeds also had higher seed size variation than plants grown from black seeds. This is the second layer of dynamic bet hedging. Thus, the maternal effect of seed heteromorphism is dual dynamic bet hedging. Furthermore, for seed traits we verified for the first time the theoretical prediction that an increase in offspring size variability induces an increase in the mean size of offspring.
Copy number variations (CNVs), as an important source of genetic variation, can affect a wide range of phenotypes by diverse mechanisms. The somatostatin receptor 2 (SSTR2) gene plays important roles in cell proliferation and apoptosis. Recently, this gene was mapped to a CNV region, which encompasses quantitative trait loci of cattle economic traits including body weight, marbling score, etc. Therefore, SSTR2 CNV may exhibit phenotypic effects on cattle growth traits. In the current study, distribution of SSTR2 gene CNVs was investigated in six Chinese cattle breeds (XN, QC, NY, JA, LX and PN), and the results showed higher CNV polymorphisms in XN, QC and NY cattle. Next, association analysis between growth traits and SSTR2 CNV was performed for XN, QC and NY cattle. In NY, individuals with fewer copies showed better performance than those with more copies. Further, the effects of SSTR2 CNV on the SSTR2 mRNA level were also investigated, but revealed no significant correlation in either muscle or adipose tissue of adult NY cattle. The results suggested the potential for use of SSTR2 CNV as a marker for the molecular breeding of NY cattle.
We study the shape and motion of gas bubbles in a liquid flowing through a horizontal or slightly inclined thin annulus. Experimental data show that in the horizontal annulus, bubbles develop a unique ‘tadpole-like’ shape with a semi-circular cap and a highly stretched tail. As the annulus is inclined, the bubble tail tends to vanish, resulting in a significant decrease of bubble length. To model the bubble evolution, the thin annulus is conceptualised as a ‘Hele-Shaw’ cell in a curvilinear space. The three-dimensional flow within the cell is represented by a gap-averaged, two-dimensional model, which achieved a close match to the experimental data. The numerical model is further used to investigate the effects of gap thickness and pipe diameter on the bubble behaviour. The mechanism for the semi-circular cap formation is interpreted based on an analogous irrotational flow field around a circular cylinder, based on which a theoretical solution to the bubble velocity is derived. The bubble motion and cap geometry is mainly controlled by the gravitational component perpendicular to the flow direction. The bubble elongation in the horizontal annulus is caused by the buoyancy that moves the bubble to the top of the annulus. However, as the annulus is inclined, the gravitational component parallel to the flow direction becomes important, causing bubble separation at the tail and reduction in bubble length.
Hemostasis, a process which causes bleeding to stop, can be enhanced using chitosan; but the detailed mechanism is unclear. Red blood cells (RBCs) adhere to chitosan because of their opposite charges, but the adhesion force is small, 3.83 pN as measured here using an optical tweezer, such that the direct adhesion cannot be the sole cause for hemostasis. However, it was observed in this study that layer structures of aggregated RBCs were formed next to chitosan objects in both static and flowing environments, but not formed next to cotton and rayon yarns. The layer structure is the clue for the initiation of hemostatsis. Through the supporting measurements of zeta potentials of RBCs and pH's using blood-chitosan mixtures, it is proposed here that the formation of the RBC layer structure next to chitosan objects is due to the reduction of repulsive electric double layer force between RBCs, because of the association of H+ deprotonated from chitosan with COO− on RBC membrane, under the DLVO (Derjaguin-Landau-Verwey-Overbeek) theory. The results are beneficial for designing effective chitosan-based wound dressings, and also for general biomedical applications.
Faraday rotators in optical isolators, typically composed of iron garnets, are photonic analogues of electrical diodes in that they do not allow reciprocal transmission of light. Isolators are especially important for blocking back-reflected light from reaching source lasers, as such feedback gives rise to unwanted noise and instabilities. In commonly implemented photonic integrated circuits (PICs), isolation is the only critical function that cannot yet be achieved by direct integration. While several techniques have been explored for integrating high-gyrotropy garnets into silicon-on-insulator PICs, this article focuses on sputter deposition, which is the most up-scalable process. High-gyrotropy Ce-doped yttrium iron garnet on nongarnet substrates can be made by sputter deposition with the use of garnet seed layers. Because these seed layers can compromise device performance, seed layer-free terbium iron garnet (TIG) has also recently been developed. Careful doping of TIG can produce Faraday rotations with opposite chiralities, which enable new device designs. Most optical isolator designs involve two-dimensional transverse magnetic-mode structures, such as interferometers or ring resonators, which employ nonreciprocal phase shift. One-dimensional Faraday rotation waveguides with quasi-phase matching have been shown to enable direct integration of isolators for all modes, including the transverse electric mode of lasers currently available for fully integrated PICs.
ZnFe2O4 (ZFO) represents a promising anode material for lithium ion batteries, but there is still a lack of deep understanding of the fundamental reduction mechanism associated with this material. In this paper, the complete visualization of reduction/oxidation products irrespective of their crystallinity was achieved experimentally through a compilation of in situ X-ray diffraction, synchrotron based powder diffraction, and ex-situ X-ray absorption fine structure data. Complementary theoretical modelling study further shed light upon the fundamental understanding of the lithiation mechanism, especially at the early stage from ZnFe2O4 up to LixZnFe2O4 (x = 2).
Li4Ti5O12 (LTO) represents a promising anode material for lithium ion batteries, however, it suffers from limitations associated with poor intrinsic electron conductivity as well as moderate ionic conductivity. Hence, to achieve the goal of creating LTO anodes with improved high-rate performance, we have put forth a number of targeted fundamental strategies. Herein we discuss the roles of controllably tuning (i) morphology, (ii) attachment modalities of carbon, and (iii) ion doping of the LTO material. In addition, we also demonstrated in situ studies of lithiation-driven structural transformations in LTO via a combination of X-ray absorption spectroscopy and ab initio calculations, which have been proven to be powerful tools to probe the negligible volume change and extraordinary stability of LTO upon repeated charge/discharge cycles.
Limbic white matter pathways link emotion, cognition, and behavior and are potentially malleable to the influences of traumatic events throughout development. However, the impact of interactions between childhood and later life trauma on limbic white matter pathways has yet to be examined. Here, we examined whether childhood maltreatment moderated the effect of combat exposure on diffusion tensor imaging measures within a sample of military veterans (N = 28). We examined five limbic tracts of interest: two components of the cingulum (cingulum, cingulate gyrus, and cingulum hippocampus [CGH]), the uncinate fasciculus, the fornix/stria terminalis, and the anterior limb of the internal capsule. Using effect sizes, clinically meaningful moderator effects were found only within the CGH. Greater combat exposure was associated with decreased CGH fractional anisotropy (overall structural integrity) and increased CGH radial diffusivity (perpendicular water diffusivity) among individuals with more severe childhood maltreatment. Our findings provide preliminary evidence of the moderating effect of childhood maltreatment on the relationship between combat exposure and CGH structural integrity. These differences in CGH structural integrity could have maladaptive implications for emotion and memory, as well as provide a potential mechanism by which childhood maltreatment induces vulnerability to later life trauma exposure.
This paper develops a model of the optimal timing of interest rate changes. With fixed adjustment costs and ongoing uncertainty, changing the interest rate involves the exercise of an option. Optimal policy therefore has a “wait-and-see” component, which can be quantified using option pricing techniques. We show that increased uncertainty makes the central bank more reluctant to change its target interest rate, and argue that this helps explain recent observed deviations from the Taylor Rule. An optimal wait-and-see policy fits the target interest rates of the Fed and Bank of Canada better than the Taylor Rule.
The neuropsychological origins of negative syndrome of schizophrenia remain elusive. Evidence from behavioural studies, which utilised emotion-inducing pictures to elicit motivated behaviour generally reported that that schizophrenia patients experienced similar affective experience as healthy individuals but failed to translate emotional salience to motivated behaviour, a phenomenon called emotion–behaviour decoupling. However, a few studies have examined emotion–behaviour decoupling in non-psychotic high-risk populations, who are relatively unaffected by medication effects.
In this study, we examined the nature and extent of emotion–behaviour decoupling in in three independent samples (65 schizophrenia patients v. 63 controls; 40 unaffected relatives v. 45 controls; and 32 individuals with social anhedonia v. 32 controls). We administered an experimental task to examine their affective experience and its coupling with behaviour, using emotion-inducing slides, and allowed participants to alter stimulus exposure using button-pressing to seek pleasure or avoid aversion.
Schizophrenia patients reported similar affective experiences as their controls, while their unaffected relatives and individuals with high levels of social anhedonia exhibited attenuated affective experiences, in particular in the arousal aspect. Compared with their respective control groups, all of the three groups showed emotion–behaviour decoupling.
Our findings support that both genetically and behaviourally high-risk groups exhibit emotion–behaviour decoupling. The familial association apparently supports its role as a putative trait marker for schizophrenia.
This study explores the growth and welfare effects of monetary policy in a scale-invariant Schumpeterian growth model with endogenous human capital accumulation. We model money demand via a cash-in-advance (CIA) constraint on research and development (R&D) investment. Our results can be summarized as follows. We find that an increase in the nominal interest rate leads to a decrease in R&D and human capital investment, which, in turn, reduces the long-run growth rates of technology and output. This result stands in stark contrast to the case of exogenous human capital accumulation in which the long-run growth rates of technology and output are independent of the nominal interest rate. Simulating the transitional dynamics, we find that the additional long-run growth effect under endogenous human capital accumulation amplifies the welfare effect of monetary policy. Decreasing the nominal interest rate from 10% to 0% leads to a welfare gain that is equivalent to a permanent increase in consumption of 2.82% (2.38%) under endogenous (exogenous) human capital accumulation.
The K-type and H-type transitions of a natural convection boundary layer of a fluid of Prandtl number 7 adjacent to an isothermally heated vertical surface are investigated by means of three-dimensional direct numerical simulation (DNS). These two types of transitions refer to different flow features at the transitional stage from laminar to turbulence caused by two different types of perturbations. To excite the K-type transition, superimposed Tollmien–Schlichting (TS) and oblique waves of the same frequency are introduced into the boundary layer. It is found that a three-layer longitudinal vortex structure is present in the boundary layer undergoing the K-type transition. The typical aligned
-shaped vortices characterizing the K-type transition are observed for the first time in pure natural convection boundary layers. For exciting the H-type transition, superimposed TS and oblique waves of different frequencies, with the frequency of the oblique waves being half of the frequency of the TS waves, are introduced into the boundary layer. Unlike the three-layer longitudinal vortex structure observed in the K-type transition, a double-layer longitudinal vortex structure is observed in the boundary layer undergoing the H-type transition. The successively staggered
-shaped vortices characterizing the H-type transition are also observed in the downstream boundary layer. The staggered pattern of
-shaped vortices is considered to be caused by temporal modulation of the TS and oblique waves. Interestingly the flow structures of both the K-type and H-type transitions observed in the natural convection boundary layer are qualitatively similar to those observed in Blasius boundary layers. However, an analysis of turbulence energy production suggests that the turbulence energy production by buoyancy rather than Reynolds stresses dominates the K-type and H-type transitions. In contrast, the turbulence energy production by Reynolds stresses is the only factor contributing to the transition in Blasius boundary layers.
Laser-induced damage threshold (LIDT) is an important parameter used to describe the resistance of optical thin films to laser damage. The service life and cost of optical systems depend on the LIDT of the film. Thus, the precision with which the film's LIDT can be measured impacts how well the service life and cost of the system can be predicted. Therefore, it is important to find a precise approach to diagnose a film's laser-induced damage. In this paper, characteristics of the peak sound pressure of laser-induced plasma shock waves from thin films have been systematically investigated experimentally. We found that the peak sound pressure decays rapidly with propagation distance during air transmission. Based on a theoretical analysis of the relationship between the peak sound pressure and the laser damage to a film, we propose a method for diagnosing laser damage using the peak sound pressure of a thin film's shock wave. Our results show that this method can simplify implementation, which will provide a new method with which to diagnose laser damage to thin films.