Impact of viral drift on vaccination dynamics and patterns of seasonal influenza

BACKGROUND: Much research has been devoted to the determination of optimal vaccination strategies for seasonal influenza epidemics. However, less attention has been paid to whether this optimization can be achieved within the context of viral drift. METHODS: We developed a mathematical model that links different intra-seasonal dynamics of vaccination and infection to investigate the effect of viral drift on optimal vaccination for minimizing the total number of infections. The model was computationally implemented using a seasonal force of infection, with estimated parameters from the published literature. RESULTS: Simulation results show that the pattern of large seasonal epidemics is strongly correlated with the duration of specific cross-protection immunity induced by natural infection. Considering a random vaccination, our simulations suggest that the effect of vaccination on epidemic patterns is largely influenced by the duration of protection induced by strain-specific vaccination. We found that the protection efficacy (i.e., reduction of susceptibility to infection) of vaccine is a parameter that could influence these patterns, particularly when the duration of vaccine-induced cross-protection is lengthened. CONCLUSIONS: Given the uncertainty in the timing and nature of antigenically drifted variants, the findings highlight the difficulty in determining optimal vaccination dynamics for seasonal epidemics. Our study suggests that the short- and long-term impacts of vaccination on seasonal epidemics should be evaluated within the context of population-pathogen landscape for influenza evolution

Hydrochemical Effect of Different Quality of Water on the Behaviour of an Expansive Soil During Wetting and Drying Cycles

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.The effect of quality of water on deformation, pH, EC (electrical conductivity) and osmotic suction was studied for an expansive soil during wetting and drying tests. The cyclic wetting and drying tests were conducted on samples of an expansive soil in a modified oedometer flooded with distilled, acidic and saline water. During the tests axial deformation of the samples was recorded continuously. pH and EC of pore water and reservoir water were measured through duplicated samples in a conventional oedometer. Osmotic suction was calculated based on the values of EC. The results show that the magnitude of deformation depends on the quality of the water and the deformation attained an equilibrium condition after almost four cycles. pH, EC and osmotic suction decreased with increasing suction. Copyright © 2016 John Wiley & Sons, Ltd

Consolidation behavior of an unsaturated silty soil during drying and wetting

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.In this work, the effect of hysteresis phenomenon on the consolidation behavior of an unsaturated silty soil was investigated through a program of experimental tests. Compacted samples were prepared by the slurry method and experimental tests were carried out in a double-walled triaxial cell. Consolidation tests were conducted by the ramping method at suctions of 0, 100, 200, 250 and 300 kPa on drying and wetting paths of the soil water characteristic curve. The results show that the paths of specific water volume and specific volume are not consistent during stabilization in either condition (drying or wetting). In addition, the yield stress for the wetting path is higher than that for drying. The trend of variations of the specific water volume during loading is similar to the consolidation curves for different suction. For both conditions of drying and wetting, the slope and intercept of the virgin line due to variations of specific volume and specific water volume are a function of suction. While their values decrease with increasing suction, these values are higher for the dry path than wetting

Waiting for the Perfect Vaccine

Vaccination has proven to be the most effective public health measure in the fight against various infectious diseases. For emerging or re-emerging diseases, a highly efficacious vaccine may not be available at the start of an outbreak. Timelines for availability of a safe and effective vaccine may significantly affect disease dynamics, its burden, and the healthcare resource utilization. Mitigating this impact may then rely on low-efficacy vaccines that may be rapidly produced and distributed to at-risk populations at the early stages of an outbreak. With the expectation for arrival of a more effective vaccine at a later stage of the outbreak, the optimal vaccination coverage with the existing, low-efficacy vaccines is elusive. While flattening the outbreak if a significant proportion of the susceptible population is vaccinated with a low-efficacy vaccine, the overall infections may not be minimized if a small proportion of the population left unvaccinated when a highly efficacious vaccine becomes available. The optimal coverage for early vaccination could thus depend on several parameters including the efficacy of the currently available vaccines, arrival timing of a more effective vaccine and its efficacy, and the transmissibility of the disease. Here, we develop a deterministic system of differential equations to investigate the optimal vaccination coverage with a low-efficacy vaccine within the aforementioned parameter space. Despite simplifying assumptions, we illustrate that minimizing the overall infections does not necessarily correspond to the highest coverage of early vaccination. However, a high vaccination coverage, even with a low-efficacy vaccine, may still contribute to alleviating severe disease outcomes and reducing healthcare resource utilization

Effect of hysteresis on the critical state behavior of an unsaturated silty soil

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordSome or all data, models, or code generated or used during the study are available from the corresponding author by request.In this paper the effect of hysteresis on the critical state behavior of unsaturated soils is investigated through conducting a number of controlled suction triaxial tests on samples of an unsaturated silty soil. The slurry method was used for preparing the samples for the main tests. The tests were carried out in a double-walled triaxial cell. In the experiments the samples were consolidated isotropically to virgin state at suctions of 0, 100, 200, 250, and 300 kPa on drying and wetting paths of soil water characteristic curve. Then they were sheared under constant suction at various constant cell pressures. The results of the drained triaxial tests were used to determine the effect of the hysteresis phenomenon on the characteristics of the critical state framework. The obtained data were examined in terms of mean net Bishop's stress (p) (by including degree of saturation) or p¯ (i.e., the mean total stress in excess of pore-air pressure), deviator stress (q), suction (s), and specific volume (v) as state variables. The results show that the critical state lines (CSLs) for the dry and wet paths are not parallel for different suctions in the q:p∗ or q:p¯ space. The slopes and intercepts of the CSLs in this space are functions of suction. In addition, the critical state lines in the v:Ln p or v:Ln p¯ plane are not parallel for drying and wetting paths and the slope and intercept of them are also functions of suction. The results also indicated that two frameworks showed similar trends of critical state parameters but the framework based on p is more reliable than the one based on the p¯

Comparison of perineal repair techniques of continuous and standard interrupted suturing in normal vaginal delivery

Background and aim: Post-delivery surgical repair of the perineal region is frequently associated with pain and discomfort. The surgical technique may play a role in the intensity of pain and the wound healing process. This study was conducted to compare the influence of applying standard continuous versus interrupted suturing on pain sensation and the frequency of wound infection following episiotomy. Methods: In a randomized double blind clinical trial, 148 healthy women with normal vaginal delivery and sustained episiotomy were studied in the Hajar hospital, Shahrekord. In one group, perineal muscles, fascia and skin tissues were repaired with continuous non-locking sutures. Standard interrupted locking suturing was applied for the next group. Pain feeling and wound infection were evaluated at 2 hours, 10th and 40th days of post-delivery by Visual Analog Scale and the signs of discoloration of skin, edema, purulent discharge, and wound dehiscence, respectively. Data were analyzed by t-student, X2 and Mann-Whitney tests. Results: Pain intensity, the amount of consumed suturing material and the allocated time were less in the cases with continuous suturing (P<0.001). The mean of pain intensity was 2.66±2.5 versus 3.84±2.56 and 0.53±1.63 versus 0.6±1.04 at 10th and 40th days after delivery in continuous and standard interrupted suturing groups, respectively (P<0.05). Signs of wound infection were observed only in 4 cases (12.5%), all of which belonged to the standard interrupted suturing group. There was a statistically significant inter-group difference in terms of the frequency of observed wound infection (P<0.05). Conclusions: The pain intensity and the chance of wound infection is less in continuous suturing of episiotomy wounds. It also is a safer and more cost-effective method as it lowers the bedding time of the mother and needs for surgical material

Tensile strained InxGa1−xPIn_{x}Ga_{1-x}P membranes for cavity optomechanics

We investigate the optomechanical properties of tensile-strained ternary InGaP nanomembranes grown on GaAs. This material system combines the benefits of highly strained membranes based on stoichiometric silicon nitride, with the unique properties of thin-film semiconductor single crystals, as previously demonstrated with suspended GaAs. Here we employ lattice mismatch in epitaxial growth to impart an intrinsic tensile strain to a monocrystalline thin film (approximately 30 nm thick). These structures exhibit mechanical quality factors of 2*10^6 or beyond at room temperature and 17 K for eigenfrequencies up to 1 MHz, yielding Q*f products of 2*10^12 Hz for a tensile stress of ~170 MPa. Incorporating such membranes in a high finesse Fabry-Perot cavity, we extract an upper limit to the total optical loss (including both absorption and scatter) of 40 ppm at 1064 nm and room temperature. Further reductions of the In content of this alloy will enable tensile stress levels of 1 GPa, with the potential for a significant increase in the Q*f product, assuming no deterioration in the mechanical loss at this composition and strain level. This materials system is a promising candidate for the integration of strained semiconductor membrane structures with low-loss semiconductor mirrors and for realizing stacks of membranes for enhanced optomechanical coupling.Comment: 10 pages, 3 figure