Latent Time Research Articles

Dengue Infection Susceptibility of Five Aedes aegypti Populations from Manaus (Brazil) after Challenge with Virus Serotypes 1-4.

The successful spread and maintenance of the dengue virus (DENV) in mosquito vectors depends on their viral infection susceptibility, and parameters related to vector competence are the most valuable for measuring the risk of viral transmission by mosquitoes. These parameters may vary according to the viral serotype in circulation and in accordance with the geographic origin of the mosquito population that is being assessed. In this study, we investigated the effect of DENV serotypes (1–4) with regards to the infection susceptibility of five Brazilian Ae. aegypti populations from Manaus, the capital of the state of Amazonas, Brazil. Mosquitoes were challenged by oral infection with the DENV serotypes and then tested for the presence of the arbovirus using quantitative PCR at 14 days post-infection, which is the time point that corresponds to the extrinsic incubation period of Ae. aegypti when reared at 28 °C. Thus, we were able to determine the infection patterns for DENV-1, -2, -3 and -4 in the mosquito populations. The mosquitoes had both interpopulation and inter-serotype variation in their viral susceptibilities. All DENV serotypes showed a similar tendency to accumulate in the body in a greater amount than in the head/salivary gland (head/SG), which does not occur with other flaviviruses. For DENV-1, DENV-3, and DENV-4, the body viral load varied among populations, but the head/SG viral loads were similar. Differently for DENV-2, both body and head/SG viral loads varied among populations. As the lack of phenotypic homogeneity represents one of the most important reasons for the long-term fight against dengue incidence, we expect that this study will help us to understand the dynamics of the infection patterns that are triggered by the distinct serotypes of DENV in mosquitoes.

Modeling the pathological cascade of Alzheimer’s disease and related dementia markers: The MEMENTO cohort

AbstractBackgroundAlzheimer’s disease and related dementia (ADRD) are characterized by a progressive alteration of clinical (Cognitive and Physical functions) and subclinical (Neuroimaging, blood and CSF markers) features. Understanding the sequence and timing of these alterations is of primary importance to understand the natural history of ADRD and ultimately change its course. Pathological processes underlying ADRD evolve over years prior to dementia diagnostic on a time scale that is still hypothetical before any diagnosis is made. The objective of this work was to describe the sequence of markers changes in the Memento cohort by realigning the individual marker trajectories according to a latent disease time to overcome this issue.MethodMemento cohort is a French nationwide clinic‐based study which aims at better understanding the natural history of ADRD. Participants with mild cognitive impairment or subjective cognitive complaint were enrolled and followed‐up intensively for a maximum of 5 years. In an analytical sample of 2186 participants, we considered repeated measures of 12 ADRD markers including cognitive performances (memory, verbal fluency, executive function), neuroimaging measures (hippocampal volume, cortical thicknesses, white matter hyperintensities, glucose metabolism of region of interest of FDG‐PET), and CSF (Aβ42, p‐tau, t‐tau). We defined the latent disease time by an individual shift of the observed time, and simultaneously analyzed the ADRD marker trajectories according to this latent disease time using a multivariate mixed model adjusted on potential confounders.ResultAfter individual realignment of the trajectories according to the latent disease time, the temporal sequence of alterations suggested that neurodegeneration preceded cognitive decline. However, such sequence largely depended on education and ApoE4 status as illustrated in the figure. Cognitive decline appeared to be delayed among participants with high level of education, whereas changes in Aβ42 and tau proteins levels in CSF seemed to appear prior to neurodegeneration and cognitive decline mainly among ApoE ε4 carriers.ConclusionUsing longitudinal multidimensional data from a large cohort, we were able to stage participants along the pathological progression of ADRD. Our results show a large heterogeneity in temporal order markers changes which could suggest the existence of several subtypes of ADRD.

Probabilistic 4D predictive model from in-room surrogates using conditional generative networks for image-guided radiotherapy.

Shape and location organ variability induced by respiration constitutes one of the main challenges during dose delivery in radiotherapy. Providing up-to-date volumetric information during treatment can improve tumor tracking, thereby increasing treatment efficiency and reducing damage to healthy tissue. We propose a novel probabilistic model to address the problem of volumetric estimation with scalable predictive horizon from image-based surrogates during radiotherapy treatments, thus enabling out-of-plane tracking of targets. This problem is formulated as a conditional learning task, where the predictive variables are the 2D surrogate images and a pre-operative static 3D volume. The model learns a distribution of realistic motion fields over a population dataset. Simultaneously, a seq-2-seq inspired temporal mechanism acts over the surrogate images yielding extrapolated-in-time representations. The phase-specific motion distributions are associated with the predicted temporal representations, allowing the recovery of dense organ deformation in multiple times. Due to its generative nature, this model enables uncertainty estimations by sampling the latent space multiple times. Furthermore, it can be readily personalized to a new subject via fine-tuning, and does not require inter-subject correspondences. The proposed model was evaluated on free-breathing 4D MRI and ultrasound datasets from 25 healthy volunteers, as well as on 11 cancer patients. A navigator-based data augmentation strategy was used during the slice reordering process to increase model robustness against inter-cycle variability. The patient data was used as a hold-out test set. Our approach yields volumetric prediction from image surrogates with a mean error of 1.67 ± 1.68mm and 2.17 ± 0.82mm in unseen cases of the patient MRI and US datasets, respectively. Moreover, model personalization yields a mean landmark error of 1.4 ± 1.1mm compared to ground truth annotations in the volunteer MRI dataset, with statistically significant improvements over state-of-the-art.

Synthetic Difference-in-Differences

We present a new estimator for causal effects with panel data that builds on insights behind the widely used difference-in-differences and synthetic control methods. Relative to these methods we find, both theoretically and empirically, that this “synthetic difference-in-differences” estimator has desirable robustness properties, and that it performs well in settings where the conventional estimators are commonly used in practice. We study the asymptotic behavior of the estimator when the systematic part of the outcome model includes latent unit factors interacted with latent time factors, and we present conditions for consistency and asymptotic normality. (JEL C23, H25, H71, I18, L66)

Witnessing latent time correlations with a single quantum particle

When a noisy communication channel is used multiple times, the errors occurring at different times generally exhibit correlations. Classically, these correlations do not affect the evolution of individual particles: a single classical particle can only traverse the channel at a definite moment of time, and its evolution is insensitive to the correlations between subsequent uses of the channel. In stark contrast, here we show that a single quantum particle can sense the correlations between multiple uses of a channel at different moments of time. In an extreme example, we show that a channel that outputs white noise when the particle is sent at a definite time can exhibit correlations that enable a perfect transmission of classical bits when the particle is sent at a superposition of two times. In contrast, we show that, in the lack of correlations, a single particle sent at a superposition of two times undergoes an effective channel with classical capacity of at most 0.16 bits. When multiple transmission lines are available, time correlations can be used to simulate the application of quantum channels in a coherent superposition of alternative causal orders, and even to provide communication advantages that are not accessible through the superposition of causal orders.

Estimation of Stress-Strength Reliability for Multicomponent System with Rayleigh Data

Inference is investigated for a multicomponent stress-strength reliability (MSR) under Type-II censoring when the latent failure times follow two-parameter Rayleigh distribution. With a context that the lifetimes of the strength and stress variables have common location parameters, maximum likelihood estimator of MSR along with the existence and uniqueness is established. The associated approximate confidence interval is provided via the asymptotic distribution theory and delta method. Meanwhile, alternative generalized pivotal quantities-based point and confidence interval estimators are also constructed for MSR. More generally, when the lifetimes of strength and stress variables follow Rayleigh distributions with unequal location parameters, likelihood and generalized pivotal-based estimators are provided for MSR as well. In addition, to compare the equivalence of different strength and stress parameters, a likelihood ratio test is provided. Finally, simulation studies and a real data example are presented for illustration.

Research on the thermal performance of interlayer ventilated PCM component coupled with solar air collector

The application of solar energy for heating in buildings has the problem of heat supply and demand time mismatch. In this paper, an interlayer ventilated phase change material (PCM) component (IVPC) that can be coupled with solar air collector was proposed. The thermal performance of IVPC was tested through experiments. The results show that if IVPC completes latent heat storage, the optimal air supply temperature of solar hot air is 35 ∼ 45℃ and the air supply speed is 3 ∼ 4 m/s. The latent heat release time can be maintained for 5 h. To build an IVPC coupled with solar air collector system (IVPSS) in TRNSYS, to simulate the improvement effect of IVPC on heating temperature fluctuations, a rural building in cold regions of China was selected. IVPSS can maintain the indoor temperature of the building in the range of 8 ∼ 16℃. Compared with buildings without IVPSS, the room temperature throughout the day can be increased by 5 ∼ 8℃. IVPC can effectively use solar energy to peak load shifting, reduce room temperature fluctuations, improve indoor thermal comfort, and provide solutions for farmhouses in cold regions to use clean energy for heating.

Inference of partially observed causes for failure of Lomax competing risks model under type-II generalized hybrid censoring scheme

Time-to- failure under different causes of failure is known as a competing risks model. Practice, competing risks data can be appeared in different applications such as engineering fields or biological and medical lifetime studies as well as other related areas. Also, the causes of failure, which are competing may be partially observed. In this paper, we adopted the competing risks model with partially observed causes of failure when the latent failure times follow Lomax life distribution under type-II generalized hybrid censoring scheme. The maximum likelihood estimators of the model parameters with the associated confidence intervals are discussed. Moreover, Bayes estimators under importance sampling procedure with probability credible intervals are developed. The results are discussed using both real and simulated data sets for illustration purposes. Finally, the Monte Carlo simulation experiments are performed to assess and compare the different proposed methods with some brief comments.

Characterization and genome analysis of a broad lytic spectrum bacteriophage P479 against multidrug-resistant Escherichia coli

The increase of multi-drug resistant and multi-serotypes of pathogenic Escherichia coli has brought more severe challenge to control infection. Nowadays, bacteriophage is a promising tool to treat colibacillosis as an alternative of antibiotics. A coliphage P479, isolated from sewage of poultry farm, could lyse multiple serotypes, including not only O1, O2, O8, O9, O21, O78, O83, O145 of Avian pathogenic E. coli, but O157:H7 of Enterohaemorrhagic E. coli and O18:K1:H7 Neonatal meningitis E. coli. Additionally, P479 could also lyse multi-drug resistant E. coli. These indicated that P479 had good lytic ability. One-step growth curve revealed that the latent time period of P479 was 10 min and the burst size was about 318 PFU/cell. Stability tests demonstrated that P479 had good stability under various temperature (4 to 50 °C) and pH (3 to11) conditions. P479 contained of a linear, double-stranded DNA molecule of 172,033 bp with 40.3% GC content. P479 contained 296 putative coding sequences (CDSs) and two tRNA genes. Based on genomic comparison, P479 was classified as a member of genus Gaprivervirus, subfamily Tevenvirinae, family Myoviridae, order Caudovirales. No known virulent or lysogenic genes were detected in the genome of P479, manifesting P479 was safe to adhibit. Antibacterial activity in vitro manifested that P479 has varying degrees bacteriostatic activity against different bacteria. According to the above properties, P479 has the potential to be applied in phage therapy in the future.

Impact of extrinsic incubation temperature on natural selection during Zika virus infection of Aedes aegypti and Aedes albopictus.

Arthropod-borne viruses (arboviruses) require replication across a wide range of temperatures to perpetuate. While vertebrate hosts tend to maintain temperatures of approximately 37°C—40°C, arthropods are subject to ambient temperatures which can have a daily fluctuation of > 10°C. Temperatures impact vector competence, extrinsic incubation period, and mosquito survival unimodally, with optimal conditions occurring at some intermediate temperature. In addition, the mean and range of daily temperature fluctuations influence arbovirus perpetuation and vector competence. The impact of temperature on arbovirus genetic diversity during systemic mosquito infection, however, is poorly understood. Therefore, we determined how constant extrinsic incubation temperatures of 25°C, 28°C, 32°C, and 35°C control Zika virus (ZIKV) vector competence and population dynamics within Aedes aegypti and Aedes albopictus mosquitoes. We also examined fluctuating temperatures which better mimic field conditions in the tropics. We found that vector competence varied in a unimodal manner for constant temperatures peaking between 28°C and 32°C for both Aedes species. Transmission peaked at 10 days post-infection for Aedes aegypti and 14 days for Aedes albopictus. Conversely, fluctuating temperature decreased vector competence. Using RNA-seq to characterize ZIKV population structure, we identified that temperature alters the selective environment in unexpected ways. During mosquito infection, constant temperatures more often elicited positive selection whereas fluctuating temperatures led to strong purifying selection in both Aedes species. These findings demonstrate that temperature has multiple impacts on ZIKV biology, including major effects on the selective environment within mosquitoes.

Oral susceptibility of aedine and culicine mosquitoes (Diptera: Culicidae) to Batai Orthobunyavirus

BackgroundA number of zoonotic mosquito-borne viruses have emerged in Europe in recent decades. Batai virus (BATV), a member of the genus Orthobunyavirus, is one example of a relatively newly emerged mosquito-borne virus, having been detected in mosquitoes and livestock. We conducted vector competency studies on three mosquito species at a low temperature to assess whether Aedes and Culex mosquito species are susceptible to infection with BATV.MethodsColonised lines of Aedes aegypti and Culex pipiens and a wild-caught species, Aedes detritus, were orally inoculated with BATV strain 53.2, originally isolated from mosquitoes trapped in Germany in 2009. Groups of blood-fed female mosquitoes were maintained at 20 °C for 7 or 14 days. Individual mosquitoes were screened for the presence of BATV in body, leg and saliva samples for evidence of infection, dissemination and transmission, respectively. BATV RNA was detected by reverse transcription-PCR, and positive results confirmed by virus isolation in Vero cells.ResultsAedes detritus was highly susceptible to BATV, with an infection prevalence of ≥ 80% at both measurement time points. Disseminated infections were recorded in 30.7–41.6% of Ae. detritus, and evidence of virus transmission with BATV in saliva samples (n = 1, days post-infection: 14) was observed. Relatively lower rates of infection for Ae. aegypti and Cx. pipiens were observed, with no evidence of virus dissemination or transmission at either time point.ConclusionsThis study shows that Ae. detritus may be a competent vector for BATV at 20 °C, whereas Ae. aegypti and Cx. pipiens were not competent. Critically, the extrinsic incubation period appears to be ≤ 7 days for Ae. detritus, which may increase the onward transmissibility potential of BATV in these populations.Graphical

4-Hydroxy-3,5-di-tret-butyl cinnamic acid restores the activity of the hippocampal mitochondria in rats under permanent focal cerebral ischemia.

Objective(s):Ischemic stroke is a disease with complex pathogenesis that requires timely and rational pharmacological intervention. One possible treatment for this condition may be to improve mitochondrial function as part of neuroprotective therapy.Materials and Methods:Cerebral ischemic damage was reproduced by middle cerebral artery permanent occlusion in Wistar male rats. 4-hydroxy-3,5-di-tretbutyl cinnamic acid was injected intraperitoneally in dose range of 25 mg/kg, 50 mg/kg, and 100 mg/kg. The time of administration was 3 days from the ischemia modeling. Further, changes in the rats’ cognitive functions in the Morris water maze test were evaluated, and the state of mitochondrial function in the hippocampal tissue was studied.Results:The study showed that the use of the studied compound dose-dependently improved mitochondrial function in the rat hippocampus. At doses of 20 mg/kg and 50 mg/kg, administration of the test substance increased citrate synthase activity by 55.1% (P<0.05) and 43.4% (P<0.05), respectively and ATP content by 25.7% (P<0.05) and 23.9% (P<0.05). Also, the intensity of oxidative stress (activity of antioxidant enzymes increase whereas the concentration of TBARS reduces) and apoptosis (calcium content, concentration of apoptosis-inducing factor, and caspase-3 activity decrease; latent time of mitochondrial transition permeability pore opening increase) decreased against the background of administration of the test compound. At a dose of 100 mg/kg, the studied compound showed less effectiveness.Conclusion:Administration of 25 mg/kg and 50 mg/kg 4-hydroxy-3,5-di-tretbutyl cinnamic acid demonstrated neuroprotection action on hippocampal cells under the conditions of irreversible brain ischemia.

Вибухо-індукована нейротравма (патофізіологічні та патоморфологічні особливості)

The article presents the results of pathophysiological and pathomorphological features which were studied in experimental blust-induced neurotrauma in rats. The relevance of this study is associated with the frequent blust neurotrauma resulting from the use of explosives in military conflicts. At the same time, neurotrauma is more common, which is clinically manifested by cognitive impairment, even with mild and moderate severity. This, in turn, leads to complications and disability for young people. The purpose of the work was to study the consequences of the air-shock wave influence on the functional and morphological states of the central nervous system. Materials and methods. The studies were carried out on 36 white male Wistar rats 5-7 months old, weighing 180-220 g. The rats were divided into two groups: I – experimental group (n=18), the animals of which were anesthetized with halothane, fixed and explosion-induced neurotraum was simulated by generating a baroacoustic wave with an excess pressure of 26.4 ± 3.6 kPa. II group was a control group (n=18). Functional changes were investigated in the Barnes maze. For pathomorphological examination, brain sections were stained with hematoxylin and eosin. The animals were kept in standard conditions and in the standard diet of the vivarium, all studies were conducted in accordance with modern international requirements and norms of humane treatment of animals (Council of Europe Convention dated 18.03.1986 (Strasbourg); Helsinki Declaration 1975, revised and supplemented in 2000, Law of Ukraine dated 21.02.2006 No. 3447-IV), which is evidenced by an extract from the protocols of the meeting of the commission on biomedical ethics. Results and discussion. Analysis of the results of memory studies in the Barnes maze showed a significant (Р &lt;0.05) increase in the latent time of entering the shelter in rats of the experimental group in the acute and early post-traumatic period, which indicates memory impairment. General characteristics of the rats behavior in the experimental group showed an increase in anxiety and disorientation. The increase in research on "fake shelters" and the chaotic movement around the facility was evidenced. Analysis of frontal histological sections of the rat brain in the dynamics of the explosion-induced neurotrauma development showed the presence of characteristic signs in the form of diffuse microhemorrhages in the hippocampus zone in the acute period of injury, diffuse areas of perivascular and pericellular edema in the early post-traumatic period and paretic dilated capillaries in the structure of the cerebral region on 2nd-3rd week of the post-traumatic period. Conclusion. Thus, quantitative (increased latent time) and qualitative (increased anxiety) signs of impaired orientational-spatial memory and the development of specific pathomorphological signs of explosive brain damage in rats of the experimental group were established

Characterization of a New and Efficient Polyvalent Phage Infecting E. coli O157:H7, Salmonella spp., and Shigella sonnei.

Ongoing outbreaks of foodborne diseases remain a significant public health concern. Lytic phages provide promising attributes as biocontrol agents. This study characterized KFS-EC3, a polyvalent and lytic phage, which was isolated from slaughterhouse sewage and purified by cesium chloride density centrifugation. Host range and efficiency of plating analyses revealed that KFS-EC3 is polyvalent and can efficiently infect E. coli O157:H7, Salmonella spp., and Shigella sonnei. KFS-EC3 had a latent time of 20 min and burst size of ~71 phages/infected cell. KFS-EC3 was stable and infectious following storage at a pH range of 3 to 11 and a temperature range of −70 °C to 60 °C. KFS-EC3 could inhibit E. coli O157:H7 growth by 2 logs up to 52 h even at the lowest MOI of 0.001. Genomic analysis of KFS-EC3 revealed that it consisted of 167,440 bp and 273 ORFs identified as functional genes, without any genes associated with antibiotic resistance, virulence, allergenicity, and lysogenicity. This phage was finally classified into the Tequatrovirus genus of the Myoviridae family. In conclusion, KFS-EC3 could simultaneously infect E. coli O157:H7, S. sonnei, and Salmonella spp. with the lowest MOI values over long periods, suggesting its suitability for simultaneous pathogen control in foods.

The Natural History of Acute Radiation-induced H-ARS and Concomitant Multi-organ Injury in the Non-human Primate: The MCART Experience.

The dose response relationship and corresponding values for mid-lethal dose and slope are used to define the dose- and time-dependent parameters of the hematopoietic acute radiation syndrome. The characteristic time course of mortality, morbidity, and secondary endpoints are well defined. The concomitant comorbidities, potential mortality, and other multi-organ injuries that are similarly dose- and time-dependent are less defined. Determination of the natural history or pathophysiology associated with the lethal hematopoietic acute radiation syndrome is a significant gap in knowledge, especially when considered in the context of a nuclear weapon scenario. In this regard, the exposure is likely ill-defined, heterogenous, and nonuniform. These conditions forecast sparing of bone marrow and increased survival from the acute radiation syndrome consequent to threshold doses for the delayed effects of acute radiation exposure due to marrow sparing, medical management, and use of approved medical countermeasures. The intent herein is to provide a composite natural history of the pathophysiology concomitant with the evolution of the potentially lethal hematopoietic acute radiation syndrome derived from studies that focused on total body irradiation and partial body irradiation with bone marrow sparing. The marked differential in estimated LD50/60 from 7.5 Gy to 10.88 Gy for the total body irradiation and partial body irradiation with 5% bone marrow sparing models, respectively, provided a clear distinction between the attendant multiple organ injury and natural history of the two models that included medical management. Total body irradiation was focused on equivalent LD50/60 exposures. The 10 Gy and 11 Gy partial body with 5% bone marrow sparing exposures bracketed the LD50/60 (10.88 Gy). The incidence, progression, and duration of multiple organ injury was described for each exposure protocol within the hematopoietic acute radiation syndrome. The higher threshold doses for the partial body irradiation with bone marrow sparing protocol induced a marked degree of multiple organ injury to include lethal gastrointestinal acute radiation syndrome, prolonged crypt loss and mucosal damage, immune suppression, acute kidney injury, body weight loss, and added clinical comorbidities that defined a complex timeline of organ injury through the acute hematopoietic acute radiation syndrome. The natural history of the acute radiation syndrome presents a 60-d time segment of multi-organ sequelae that is concomitant with the latent period or time to onset of the evolving multi-organ injury of the delayed effects of acute radiation exposure.

A Guide to Visualizing Trajectories of Change With Confidence Bands and Raw Data

This tutorial is aimed at researchers working with repeated measures or longitudinal data who are interested in enhancing their visualizations of model-implied mean-level trajectories plotted over time with confidence bands and raw data. The intended audience is researchers who are already modeling their experimental, observational, or other repeated measures data over time using random-effects regression or latent curve modeling but who lack a comprehensive guide to visualize trajectories over time. This tutorial uses an example plotting trajectories from two groups, as seen in random-effects models that include Time × Group interactions and latent curve models that regress the latent time slope factor onto a grouping variable. This tutorial is also geared toward researchers who are satisfied with their current software environment for modeling repeated measures data but who want to make graphics using R software. Prior knowledge of R is not assumed, and readers can follow along using data and other supporting materials available via OSF at https://osf.io/78bk5/ . Readers should come away from this tutorial with the tools needed to begin visualizing mean trajectories over time from their own models and enhancing those plots with graphical estimates of uncertainty and raw data that adhere to transparent practices in research reporting.

The Extrinsic Incubation Period of Zika Virus in Florida Mosquitoes Aedes aegypti and Ae. albopictus.

The Asian genotype of Zika virus (ZIKV) emerged in Brazil in 2015 and subsequently spread throughout the Americas. In July 2016, Florida experienced its first locally acquired ZIKV infection in the continental U.S. Concerns about health risks from ZIKV infection have increased the need to investigate the interactions between potential mosquito vectors and ZIKV. The time it takes for an arbovirus to propagate within a mosquito, and become transmissible, is the extrinsic incubation period (EIP). The EIP for potential mosquito vectors in Florida is unknown. To address this gap in the understanding of ZIKV epidemiology, Florida Aedes aegypti (L.) and Ae. albopictus (Skuse) were orally exposed to ZIKV infected blood meals and fully engorged mosquitoes were held at a constant temperature of 28 °C through the duration of the experiment. Saliva expectorates were collected from cohorts of mosquitoes and tested for the presence of ZIKV at three-day intervals over a period of 24 days to allow for an evaluation of the EIP of the emergent Asian lineage of ZIKV. High rates of infected bodies in Ae. albopictus (75–94%) and Ae. aegypti (68–86%) were observed throughout the incubation period, which did not differ by species. Higher rates of disseminated infection were observed later during the incubation period but did not differ between species. We calculated the 50% EIP to be shorter in Ae. albopictus than Ae. aegypti (16.2 and 18.2 days post infection, respectively). The competence for ZIKV observed in both species may contribute to high rates of ZIKV transmission in Florida populations.

A model for analysing the dynamics of the second wave of corona virus (COVID--19) in Nigeria

The resurgence of the coronavirus (COVID--19) disease is rapidly taking its toll on many nations across the globe. As the situation rapidly evolves, the entire world is faced with difficult and challenging moment and the need to be safe from the disease. Several international efforts are geared towards the production of effective vaccine for curing the disease. But, pending the availability of such vaccine, the need to flatten the curves is now the top priority of both governmental and non-governmental organisations in Nigeria. Estimation of the basic reproduction number of the disease is crucial to understanding its dynamics and making suitable preventive policies that will slow the spread and ultimately flatten the curves. In this work, we propose a compartmental--based model for analysing the dynamics of the pandemics' second wave in Nigeria taking into consideration, the current control measures. Using the Quasi--Newton algorithm, the model is fitted to the available data provided by Nigeria Centre for Disease Control (NCDC), World Health Organization (WHO) and accessible on the Wolfram Data Repository. The basic reproduction number of the second wave of the disease in Nigeria is estimated using the model. The model was also used to estimate the infection rate, average latent time, average recovery rate and average mortality rate of the disease. Efficiency of the current control measures is also measured. Forecast of the turning points and possible vanishing time of the virus in Nigeria are made. The infection rate, average latent time, average recovery rate and average mortality rate of the disease are estimated. Also, the basic reproduction number of the disease in Nigeria is estimated. Predictions on the turning points and possible vanishing time of the virus in Nigeria are made. Recommendations on how to manage the resurgence of the disease in Nigeria are also suggested.

The Effect of Fluctuating Incubation Temperatures on West Nile Virus Infection in Culex Mosquitoes.

Temperature plays a significant role in the vector competence, extrinsic incubation period, and intensity of infection of arboviruses within mosquito vectors. Most laboratory infection studies use static incubation temperatures that may not accurately reflect daily temperature ranges (DTR) to which mosquitoes are exposed. This could potentially compromise the application of results to real world scenarios. We evaluated the effect of fluctuating DTR versus static temperature treatments on the infection, dissemination, and transmission rates and viral titers of Culex tarsalis and Culex quinquefasciatus mosquitoes for West Nile virus. Two DTR regimens were tested including an 11 and 15 °C range, both fluctuating around an average temperature of 28 °C. Overall, no significant differences were found between DTR and static treatments for infection, dissemination, or transmission rates for either species. However, significant treatment differences were identified for both Cx. tarsalis and Cx. quinquefasciatus viral titers. These effects were species-specific and most prominent later in the infection. These results indicate that future studies on WNV infections in Culex mosquitoes should consider employing realistic DTRs to reflect interactions most accurately between the virus, vector, and environment.

Phenotypic and genotypic characterization of the new Bacillus cereus phage SWEP1.

A new Bacillus cereus phage, SWEP1, was isolated from black soil. The host lysis activity of phage SWEP1 has a relatively short latent time (20min) and a small burst size of 83 PFU. The genome of SWEP1 consists of 162,461bp with 37.77% G+C content. The phage encodes 278 predicted proteins, 103 of which were assigned functionally. No tRNA genes were found. Comparative genomics analysis indicated that SWEP1 is related to Bacillus phage B4 (86.91% identity, 90% query coverage). Phenotypic and genotypic characterization suggested that SWEP1 is a new member of a new species in the genus Bequatrovirus, family Herelleviridae.