Attack Rate Research Articles

Does the superfluous killing exhibited by spiders mask the functional response parameters? A case study from the perspective of biological control

AbstractThe meadow spittlebug Philaenus spumarius L. (Hemiptera: Aphrophoridae) is a xylem‐sap feeder and the most abundant and widespread vector of Xylella fastidiosa (Xanthomonadales: Xanthomonadaceae) throughout Europe. Control strategies for the disease are based on containment and eradication measures regulated by the European Union. Within the context of biological control, the use of natural enemies aims at limiting the insect vector population in agroecosystems. Spiders are generalist predators with potential as biological control agents occupying all the habitats within crops. Crab spiders (Thomisidae) could be potential natural enemies against P. spumarius. The functional response (FR) of a predator represents the intake rate as a function of food availability and allows estimating feeding behaviour parameters such as the prey handling time and attack rate. However, spiders often kill more prey than they consume, unveiling their capacity as natural enemies. We assessed and compared the FR of Xysticus acerbus (Thomisidae) fed on P. spumarius in the laboratory considering (1) the total number of dead individuals and (2) only the consumed ones. We found that although both FRs were of type‐II, they significantly differed. The values of attack rate and handling time for consumed were 0.1 and 3.6, respectively, while for dead, the attack rate was 0.3 and 1.1, being both significantly different. Moreover, the number of overkilled individuals reached a plateau at the highest prey densities. Xysticus acerbus could be a potential natural enemy of P. spumarius. Nevertheless, we suggest that the effect of including the killed but not consumed prey individuals in FR studies using wasteful killing predators should be considered and further studied.

Intensity attacks of Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) on several corn varieties in Kediri, East Java, Indonesia

Abstract. Sudihardjo D, Samanhudi, Sholahuddin, Pujiasmanto B, Rahayu M, Setyawati A. 2023. Intensity attacks of Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) on several corn varieties in Kediri, East Java, Indonesia. Biodiversitas 24: 6979-6987. The presence of Spodoptera frugiperda J.E. Smith, 1797 attack on corn is one of the main causes of the decrease in yield. Local, composite, and hybrid corn have different characteristics and will affect intensity attack and foliar damage due to S. frugiperda attack. This study aimed to determine the intensity of the attack of several types of local corn, composites, and hybrids against S. frugiperda. The research was conducted in the Kediri region, East Java, one of the corn cultivation centers. The study used a completely randomized block design with three replications of 18 varieties of various local, composites, and hybrid corn varieties. Local corn varieties consist of Madura Putih, Kebo Bima, Manik Liu, Lameran-Latim, Seraye-Bali, Madura kuning, and Sumbawa. Composite corn varieties include Bisma, Puput Uri, Srikandi Ungu, and Sukmaraga. Furthermore, the hybrid varieties comprise ADV Jago, Bisi 18, DK 77, NK 6172, P 27, Pertiwi 3, and R7. The results showed the infestation of S. frugiperda in all corn varieties peaked at age 42 DAP, with the intensity attack reaching 100%. The lowest intensity attack rate of S. frugiperda was obtained by the Sukmaraga composite variety and the NK6172 hybrid variety tends to be more resistant to S. frugiperda attacks than composite and local varieties. All corn-tested varieties were attached by S. frugiperda, which varied for the percentage of plant damage, severity level, and the time the pest attack first attacked. The clustering groups of each corn variety were based on the intensity attack of S. frugiperda, number of larvae, severity level and early infestation founded group resistant, which have less foliar damage due to S. frugiperda larvae attacks consisting of 5 varieties: Madura kuning, Madura Putih, Bisma, NK6172, and Srikandi Ungu.

Functional response and mutual interference in the parasitoid Coptera haywardi (Oglobin) (Hymenoptera: Diapriidae) attacking Anastrepha ludens (Loew) (Diptera: Tephritidae) pupae.

Functional response and mutual interference are important attributes of natural enemies that should be analysed in species with the potential to be used as biological control agents in order to increase the predictive power of the possible benefits and/or consequences of their release in the field. Our main objective was to determine the functional response and mutual interference of Coptera haywardi (Oglobin), a pupal parasitoid of economically important fruit flies (Diptera: Tephritidae). The functional response of C. haywardi on A. ludens pupae corresponded to a type II model, with an attack rate of 0.0134 host pupa/h and a handling time of 1.843 h, which reveals a meticulous selection process of pupal hosts. The effect of mutual interference among foraging females was negatively correlated with increased parasitoid density in the experimental arena, showing a gradual decline in attack rate per individual female. The increase in the number of foraging females also had an impact on the number of oviposition scars per pupa and the number of immature parasitoids per dissected pupa, but not on the percentage of adult emergence or the sex ratio. Our results suggest that C. haywardi could act as a complementary parasitoid in the control of fruit fly pupae, since the random distribution of these pupae in the soil would decrease the possibility of aggregation and mutual interference between foraging females.

Comparing Complication Rates of Transcatheter Aortic Valve Replacement to Surgical Aortic Valve Replacement

Background/Objective: Transcatheter aortic valve replacement (TAVR) and surgical aortic valve replacement (SAVR) are the two procedures used to treat severe symptomatic aortic stenosis. One of the most feared outcomes of both procedures is stroke. Conduction abnormalities and arrhythmias after TAVR are relatively common, but few studies have been done comparing the rate of these events between TAVR and SAVR. The objective of our study is to find if there are any differences between the rates of stroke, conduction abnormalities, and arrhythmias between patients that have undergone TAVR and patients that have undergone SAVR. Methods: The CRC/Sidus Real World Evidence Cardiology Dataset was used to obtain samples for this project. Patients who underwent TAVR and SAVR were identified using CPT codes. These two cohorts of patients were tracked for complications between 0 to 30 days after the procedure and between 0 days to 1 year after the procedure using ICD-10 codes. Results: Patients who underwent TAVR (n=3621) were much more likely to have conduction disorders and arrhythmias both in the 0-30 day range and 0 days-1 year range after the procedure compared to patients who underwent SAVR (n=2137). Cerebral infarction and transient cerebral ischemic attack rates were also higher in the TAVR group. Mortality rates for TAVR were lower than mortality rates for SAVR, both 30 days and 1 year after the procedure. Conclusion/Impact: TAVR has revolutionized aortic valve replacement and allowed many patients with aortic stenosis (many of whom are at high surgical risk) a minimally invasive option to improve their quality of life. Finding ways to reduce the rates of stroke, arrhythmias, and conduction abnormalities; for example, through improved devices and techniques, and improvedanti-thrombotic therapy, is extremely important as TAVR becomes more and more widely utilized.

Comparative Study of Integrated Pest Management and Farmer's Standard Practices for Controlling Chrysanthemum Thrips under Plastic House

Thrips is an important worldwide cause of severe damage to various host plants, especially chrysanthemums. Current management still relies on synthetic insecticides to control thrips. However, these pesticides harm the environment and promote thrips resistance. The study aimed to compare integrated pest management (IPM) and farmer’s standard practices to control <em>Thrips parvispinus</em> on two chrysanthemum varieties and calculate the cost-benefit ratio of both pest control practices. Two chrysanthemum cultivars were planted in plastic houses to compare IPM and farmer’s standard practices. The observed variables included thrips density, attack and damage rates, cut flower yield, and natural enemies abundance. Data were analyzed using ANOVA, and Tukey's HSD test identified significant differences at a 5% level. The results showed that the population of <em>T. parvispinus</em> nymphs was higher (78%) than adults. The highest adult thrips population emerges when chrysanthemums achieve the flowering phases. This study reveals that the control effects of IPM were not different from farmer’s standard practices. A holistic approach integrating several management strategies successfully controlled the thrips population while producing high-quality crops with minimal aesthetic damage. The IPM strategy against thrips showed a competitive cost and reduced synthetic insecticide applications without decreasing the quality and productivity of chrysanthemums.

Does COVID-19 Vaccination Protect Contact Persons? A Systematic Review

The protective effect of COVID-19 vaccination for contact persons is controversial. Therefore, the aim of this review was to determine whether COVID-19 vaccination provides significant protection for them. A PubMed search was carried out using the terms “unvaccinated vaccinated covid” in combination with “viral load” and “transmission”. Studies were included if they reported original comparative data on the SARS-CoV-2 viral load, duration of SARS-CoV-2 detection, or SARS-CoV-2 transmission rates. A total of 332 articles were identified, of which 68 were included and analyzed. The differences in the viral load were equivocal in 57% of the 35 studies, significantly lower in the vaccinated in 11 studies and in the unvaccinated in 3 studies. The infectious virus levels were significantly lower in the vaccinated in two out of six studies. Virus clearance was significantly faster in vaccinated subjects in two of eight studies (detection of viral RNA) and two of four studies (detection of infectious virus). The secondary attack rates were significantly lower in vaccinated index cases in 6 of 15 studies. The vaccination status of contacts was described in two of the six studies and was 31.8% and 39.9% lower in households with an unvaccinated index case. The inconsistent and variable differences in the viral load, viral clearance and secondary attack rates between vaccinated and unvaccinated individuals, especially during the omicron predominance, suggests that COVID-19 vaccination is unlikely to prevent a relevant proportion of transmissions to contact persons, taking into account the relevance of the immunological status of the contact population (vaccination rates and previous infection).

Transmission characteristics and inactivated vaccine effectiveness against transmission of the SARS-CoV-2 Omicron BA.2 variant in Shenzhen, China.

We conducted a retrospective cohort study to evaluate the transmission risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.2 variant and the effectiveness of inactivated COVID-19 vaccine boosters in Shenzhen during a BA.2 outbreak period from 1 February to 21 April 2022. A total of 1,248 individuals were infected with the BA.2 variant, and 7,855 close contacts were carefully investigated. The risk factors for the high secondary attack rate of SARS-CoV-2 infection were household contacts [adjusted odds ratio (aOR): 1.748; 95% confidence interval (CI): 1.448, 2.110], younger individuals aged 0-17 years (aOR: 2.730; 95% CI: 2.118, 3.518), older persons aged ≥60 years (aOR: 1.342; 95% CI: 1.135, 1.588), women (aOR: 1.442; 95% CI: 1.210, 1.718), and the subjects exposed to the post-onset index cases (aOR: 8.546; 95% CI: 6.610, 11.050), respectively. Compared with the unvaccinated and partially vaccinated individuals, a relatively low risk of secondary attack was found for the individuals who received booster vaccination (aOR: 0.871; 95% CI: 0.761, 0.997). Moreover, a high transmission risk was found for the index cases aged ≥60 years (aOR: 1.359; 95% CI: 1.132, 1.632), whereas a relatively low transmission risk was observed for the index cases who received full vaccination (aOR: 0.642; 95% CI: 0.490, 0.841) and booster vaccination (aOR: 0.676; 95% CI: 0.594, 0.770). Compared with full vaccination, booster vaccination of inactivated COVID-19 vaccine showed an effectiveness of 24.0% (95% CI: 7.0%, 37.9%) against BA.2 transmission for the adults ≥18 years and 93.7% (95% CI: 72.4%, 98.6%) for the adults ≥60 years, whereas the effectiveness was 51.0% (95% CI: 21.9%, 69.3%) for the individuals of 14 days to 179 days after booster vaccination and 51.2% (95% CI: 37.5%, 61.9%) for the non-household contacts. The estimated mean values of the generation interval, serial interval, incubation period, latent period, and viral shedding period were 2.7 days, 3.2 days, 2.4 days, 2.1 days, and 17.9 days, respectively. In summary, our results confirmed that the main transmission route of Omicron BA.2 subvariant was household contact, and booster vaccination of the inactivated vaccines was relatively effective against BA.2 subvariant transmission in older people.

Personal protective measures and settings on the risk of SARS-COV-2 community transmission: a case-control study.

During the SARS-CoV-2 pandemic, nurses of primary health care has been an important role in Spain. Even so, the data obtained in the tracing have been scarcely used to investigate the possible mechanisms of transmission. Few studies focused on community transmission, evaluating the effectiveness of individual protective measures and exposure environment. The main aim of the study was to evaluate the association between individual protective measures and SARS-CoV-2 transmission in the community and to compare secondary attack rates in different exposure settings. A case-control study from contact tracing of SARS-CoV-2 index patients. COVID-19 contact tracing was led by nurses at the COVID-19 Coordinating Centre in Majorca (Spain). During the systematic tracing, additional information for this study was collected from the index patient (social-demographic variables, symptoms, the number of close contacts). And also, the following variables from their close contacts: contact place, ventilation characteristics mask-wearing, type of mask, duration of contact, shortest distance, case-contact relationship, household members, and handwashing, the test result for SARS-CoV-2 diagnostic. Close contacts with a positive test for SARS-CoV-2 were classified as "cases" and those negative as "controls." A total of 1,778 close contacts from 463 index patients were identified. No significant differences were observed between the sexes but between age groups. Overall Secondary Attack Rate (SAR) was 24.0% (95% CI: 22.0-26.0%), 36.9% (95% CI: 33.2-40.6%) in closed spaces without ventilation and 50.7% (95% CI: 45.6-55.8%) in exposure time > 24 h. A total of 49.2% of infections occurred among household members. Multivariate logistic regression analysis showed that open-air setting (OR 0.43, 95% CI: 0.27-0.71), exposure for less than 1 h (OR 0.19, 95% CI: 0.11-0.32), and wearing a mask (OR 0.49, 95% CI: 0.28-0.85) had a protective effect transmission of SARS-CoV-2 in the community. Ventilation of the space, mask-wearing and shorter exposure time were associated with a lower risk of transmission in the community. The data obtained allowed an assessment of community transmission mechanisms and could have helped to improve and streamline tracing by identifying close contacts at higher risk.

Three years of COVID-19 in children that attend the Mexican Social Security Institute's 1,350 child day-care centers, 2020-2023.

Studies have suggested that children are less likely than adults to develop COVID-19; however, with the emergence of SARS-CoV-2 variants, hospitalization and death due to this cause have increased among the youngest ones. Retrospective, descriptive analytical study of the COVID-19 cases, hospitalizations and deaths occurred in children under five years who attended in Child Day-Care Centers (Centros de Atención Infantil-CAIs) of the Mexican Social Security Institute (IMSS) from 20th July 2020 to 31st March 2023. Results were compared with Mexico's and the US's national-level data. Incidence, attack (children and workers) and mortality rates were estimated. The risks of getting sick, being hospitalized and dying due to COVID-19 were calculated by year. There were 4,369 COVID-19 cases among children from IMSS CAIs; 67 (1.5%) required hospitalization and only two deaths were reported (0.04%). Both at IMSS CAIs and at a national level in Mexico and the US, the highest incidences of COVID-19 among children under five years occurred during Omicron prevalence. The attack rate among workers (32.93%) was higher than children (4.99%). Hospitalization and mortality rates in the US decreased since the anti-COVID 19 vaccine was introduced in children older than six months, unlike the rates in Mexico, where the vaccine for this age group was not available. By the year 2020, the children that attended the IMSS CAIs were 77.3% less likely to be hospitalized; 80.9% in 2021, 93.2% in 2022, and 77.7% by March 2023, compared to same age children in Mexico. In 2021, the children that attended IMSS CAIs were 90.6% less likely to die due to COVID-19, and by March 2023, this likelihood was 34.3% lower than the rest of children in this age group in Mexico. Children that attended IMSS CAIs had a smaller risk of hospitalization and death due to COVID-19. However, the high rates of hospitalization and death due to SARS-CoV-2 in children under five years in our country point to the need and urgency of vaccination against this virus in this age group, as well as of the adherence to strict detection and medical referral protocols.

Pediatric and Young Adult Household Transmission of the Initial Waves of SARS-CoV-2 in the United States: Administrative Claims Study.

The correlates responsible for the temporal changes of intrahousehold SARS-CoV-2 transmission in the United States have been understudied mainly due to a lack of available surveillance data. Specifically, early analyses of SARS-CoV-2 household secondary attack rates (SARs) were small in sample size and conducted cross-sectionally at single time points. From these limited data, it has been difficult to assess the role that different risk factors have had on intrahousehold disease transmission in different stages of the ongoing COVID-19 pandemic, particularly in children and youth. This study aimed to estimate the transmission dynamic and infectivity of SARS-CoV-2 among pediatric and young adult index cases (age 0 to 25 years) in the United States through the initial waves of the pandemic. Using administrative claims, we analyzed 19 million SARS-CoV-2 test records between January 2020 and February 2021. We identified 36,241 households with pediatric index cases and calculated household SARs utilizing complete case information. Using a retrospective cohort design, we estimated the household SARS-CoV-2 transmission between 4 index age groups (0 to 4 years, 5 to 11 years, 12 to 17 years, and 18 to 25 years) while adjusting for sex, family size, quarter of first SARS-CoV-2 positive record, and residential regions of the index cases. After filtering all household records for greater than one member in a household and missing information, only 36,241 (0.85%) of 4,270,130 households with a pediatric case remained in the analysis. Index cases aged between 0 and 17 years were a minority of the total index cases (n=11,484, 11%). The overall SAR of SARS-CoV-2 was 23.04% (95% CI 21.88-24.19). As a comparison, the SAR for all ages (0 to 65+ years) was 32.4% (95% CI 32.1-32.8), higher than the SAR for the population between 0 and 25 years of age. The highest SAR of 38.3% was observed in April 2020 (95% CI 31.6-45), while the lowest SAR of 15.6% was observed in September 2020 (95% CI 13.9-17.3). It consistently decreased from 32% to 21.1% as the age of index groups increased. In a multiple logistic regression analysis, we found that the youngest pediatric age group (0 to 4 years) had 1.69 times (95% CI 1.42-2.00) the odds of SARS-CoV-2 transmission to any family members when compared with the oldest group (18 to 25 years). Family size was significantly associated with household viral transmission (odds ratio 2.66, 95% CI 2.58-2.74). Using retrospective claims data, the pediatric index transmission of SARS-CoV-2 during the initial waves of the COVID-19 pandemic in the United States was associated with location and family characteristics. Pediatric SAR (0 to 25 years) was less than the SAR for all age other groups. Less than 1% (n=36,241) of all household data were retained in the retrospective study for complete case analysis, perhaps biasing our findings. We have provided measures of baseline household pediatric transmission for tracking and comparing the infectivity of later SARS-CoV-2 variants.

Incidence and transmission of respiratory syncytial virus in urban and rural South Africa, 2017-2018

Data on respiratory syncytial virus (RSV) incidence and household transmission are limited. To describe RSV incidence and transmission, we conducted a prospective cohort study in rural and urban communities in South Africa over two seasons during 2017-2018. Nasopharyngeal swabs were collected twice-weekly for 10 months annually and tested for RSV using PCR. We tested 81,430 samples from 1,116 participants in 225 households (follow-up 90%). 32% (359/1116) of individuals had ≥1 RSV infection; 10% (37/359) had repeat infection during the same season, 33% (132/396) of infections were symptomatic, and 2% (9/396) sought medical care. Incidence was 47.2 infections/100 person-years and highest in children <5 years (78.3). Symptoms were commonest in individuals aged <12 and ≥65 years. Individuals 1-12 years accounted for 55% (134/242) of index cases. Household cumulative infection risk was 11%. On multivariable analysis, index cases with ≥2 symptoms and shedding duration >10 days were more likely to transmit; household contacts aged 1-4 years vs. ≥65 years were more likely to acquire infection. Within two South African communities, RSV attack rate was high, and most infections asymptomatic. Young children were more likely to introduce RSV into the home, and to be infected. Future studies should examine whether vaccines targeting children aged <12 years could reduce community transmission.

Functional response estimations of Chrysoperla carnea to different densities of Aphis craccivora and Gynaikothrips ficorum nymphs.

The functional responses of Chrysoperla carnea larvae were evaluated at different seven densities of the 3rd instar nymphs of Aphis craccivora and Gynaikothrips ficorum in order to find out the relationship between predator densities and its prey by the, and also to find out their capability for biological control of aphids and thrips. Results revealed that all tested larval instars of Ch. carnea exhibited a type II response in relation to the prey. Moreover, the coefficients of attack rate (a) and handling time (Th) was differed among various growing instars of predator and for the prey species. The 3rd instar larvae of Ch. carnea manifested the highest attacking rate (1.23 and 1.22) on the 3rd instar nymphs of A. craccivora and G. ficorum, respectively. In addition it exhibited the highest maximum predation (Na max) (50.00 and 52.63) on A. craccivora and G. ficorum nymphs, respectively as compared with the other treatments. Accordingly, Ch. carnea could be considered as a promising bio-control agent for A. craccivora and G. ficorum management.

Risk of Severe Acute Respiratory Syndrome Coronavirus 2 Transmission in Seoul, Korea.

The risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission during the endemic phase may vary from that during the previous pandemic phase. We evaluated the risk of infection in a general population with laboratory-confirmed coronavirus disease 2019 (COVID-19) in a community setting in Korea. This study included 1,286 individuals who had been in contact with an index COVID-19 case between January 24, 2020, and June 30, 2022. Variables such as age, sex, nationality, place of contact, level of contact, the status of exposed cases, period, and level of mask-wearing were assessed. Among 1,286 participants, 132 (10.30%) were confirmed to have COVID-19. With increasing age, the risk of the exposed persons contracting COVID-19 from index cases tended to increase (P <0.001), especially for people in their 70s (odds ratio = 1.24, 95% confidence interval: 1.11 - 1.40, P <0.001). We found an increasing trend in the risk of a COVID-19 exposed case becoming a secondary infection case (P <0.001) in long-term care facilities where the attack rate was high. The risk of COVID-19 transmission is high in long-term care facilities where many older adults reside. Intensive management of facilities at risk of infection and strict mask-wearing of confirmed COVID-19 cases are necessary to prevent the risk of COVID-19 infection.

Interplay of missed opportunity for vaccination and poor response to the vaccine led to measles outbreak in a slum area of Eastern Mumbai, India.

In the third week of September 2022, an outbreak of measles was reported from a slum in Eastern Mumbai, India. We sought to investigate whether failure to vaccinate or vaccine failure was the cause. We constructed an epidemic curve, drew a spot map, and calculated the attack rate and case-fatality ratio. We calculated vaccine effectiveness (VE) for one and two doses of measles vaccine in an unmatched case-control study and did stratified analysis by sex, availability of vaccination card, and migrant status. We identified 358 cases and four deaths with a 11.3% attack rate and 1.1% case fatality, both being highest among 0-24-month-old boys. The epidemic curve suggested a propagated mode of spread. The VE for two doses was 64% (95% confidence interval (CI): 23-73%) among under-5-year-old children and 70% (95% CI: 28-88%) among 5-15-year-old children. Failure to vaccinate, consequent to the COVID-19 pandemic, and vaccine hesitancy might have led to the accumulation of susceptible children in the community. Additionally, the occurrence of case-patients among vaccinated suggests reduced VE, which needs further investigation into humoral and cell-mediated immunity as well as contributory factors including nutritional status. Outbreak response immunization to complete immunization of missed and dropout children was carried out to control the outbreak.

Investigation of COVID-19 outbreak at a refugee transit centre, Kisoro District, Uganda, June-July 2022.

Due to conflict in the Democratic Republic of Congo (DRC), approximately 34,000 persons arrived at Nyakabande Transit Centre (NTC) between March and June 2022. On June 12, 2022, Kisoro District reported >330 cases of COVID-19 among NTC residents. We investigated the outbreak to assess its magnitude, identify risk factors, and recommend control measures. We defined a confirmed case as a positive SARS-CoV-2 antigen test in an NTC resident during March 1-June 30, 2022. We generated a line list through medical record reviews and interviews with residents and health workers. We assessed the setting to understand possible infection mechanisms. In a case-control study, we compared exposures between cases (persons staying ≥5 days at NTC between June 26 and July 16, 2022, with a negative COVID-19 test at NTC entry and a positive test at exit) and unmatched controls (persons with a negative COVID-19 test at both entry and exit who stayed ≥5 days at NTC during the same period). We used multivariable logistic regression to identify factors associated with contracting COVID-19. Among 380 case-persons, 206 (54.2%) were male, with a mean age of 19.3 years (SD = 12.6); none died. The attack rate was higher among exiting persons (3.8%) than entering persons (0.6%) (p<0.01). Among 42 cases and 127 controls, close contact with symptomatic persons (aOR = 9.6; 95%CI = 3.1-30) increased the odds of infection; using a facemask (aOR = 0.06; 95% CI = 0.02-0.17) was protective. We observed overcrowding in shelters, poor ventilation, and most refugees not wearing face masks. The COVID-19 outbreak at NTC was facilitated by overcrowding and suboptimal use of facemasks. Enforcing facemask use and expanding shelter space could reduce the risk of future outbreaks. The collaborative efforts resulted in successful health sensitization and expanding the distribution of facemasks and shelter space. Promoting facemask use through refugee-led efforts is a viable strategy.

OUTCOMES OF WARFARIN THERAPY FOR SECONDARY PREVENTION OF ISCHEMIC STROKE: A RETROSPECTIVE, FOLLOW-UP STUDY

Aim: Anticoagulant prophylaxis is recommended because cardioembolic ischemic stroke is associated with worse functional outcomes, increased recurrence rates, and higher mortality. This study aimed to investigate the rates of recurrent ischemic attacks and bleeding complications in patients receiving warfarin following ischemic stroke. Method: In this retrospective analysis, a total of 181 individuals who were initiated on warfarin therapy following an ischemic stroke were included in the study. These patients were subsequently monitored for a duration spanning from 1 month to as long as 16 years. The acute ischemic stroke diagnosis was established using the Trial of Org 10172 in Acute Stroke Treatment classification criteria. Patient follow-up periods, international normalized ratio (INR) levels, ischemic events, and bleeding were recorded and evaluated. Results: In the patient cohort, 97 (53.6%) were women and 84 (46.4%) were men. The recurrent ischemic stroke rate was 7.2%, major bleeding rate was 3.3%, and minor bleeding rate was 12.7%. While the average INR value during recurrent ischemic stroke was 1.69±0.31, the average INR value during bleeding complications was observed to be 3.15±1.38. The rate of minor bleeding was related to duration of warfarin use and non-valvular atrial fibrillation. Conclusion: Our results show that long-term warfarin use and non-valvular atrial fibrillation are risk factors for bleeding.

Dynamic Reconfiguration for Resilient State Estimation Against Cyber Attacks

The increasing complexity and connectivity of critical infrastructures makes it increasingly likely that they will be subject to malicious attacks that compromise operation. Recent studies have shown that these systems are vulnerable to a wide range of cyber-attacks, including False Data Injection (FDI) attacks that bypasses conventional detection techniques. Conventional security monitoring, protection, and control tools are based primarily on passive defense strategies. In this paper, we propose an approach for active defense that improves system security and the detection rate of FDI attacks. The key insight for this approach is that emerging micro-grids can utilize distributed energy resources to dynamically reconfigure the system (e.g. power flow paths), across multiple acceptable configurations. Instead of using information from only a single static configuration to detect FDI attacks, our proposed approach uses <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dynamic reconfiguration</i> to compare measured and estimated states under multiple configurations to accurately detect FDI attacks. We describe an implementation and supporting infrastructure for a secure reconfigurable microgrid. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Dynamic reconfiguration</i> also makes it more difficult for attackers to gain knowledge on the system's parameters, which increases the difficulty for attackers to construct hidden attack vectors. We evaluate our approach in the specific scenario of emerging micro-grids. We develop a novel technique for state estimation using multiple configurations and demonstrate that this approach significantly improves FDI detection accuracy.

Development of a neural network structure for recognition of attacks in computer systems

The integration of industrial control communication networks and the Internet into the Industrial Control System (ICS) increases their vulnerability to cyber-attacks, leading to devastating consequences. Traditional intrusion detection systems (IDS) mostly rely on predefined models and are trained mostly on specific cyber attacks, which means that traditional IDS cannot deal with unknown attacks In addition, most IDSs do not take into account the imbalance of ICS datasets, and therefore suffer from low accuracy and high false positives when used. In the article, we propose an NCO-double-layer DIFF_RF-OPFYTHON intrusion detection method for ICS, which consists of NCO modules, two-layer DIFF_RF modules, and OPFYTHON modules. Detected traffic will be divided into three categories by the two-layer DIFF_RF module: known attacks, unknown attacks, and normal traffic. Next, the known attacks will be classified by the OPFYTHON module into specific attacks according to the characteristics of the attack traffic. We use the NCO module to improve model inputs and improve model accuracy. The results show that the proposed method outperforms traditional intrusion detection methods such as XGboost and SVM. Detecting unknown attacks is also significant. The accuracy of the data set used in this article reaches 98.13%. The detection rate of unknown and known attacks reaches 98.21% and 95.1%, respectively. In this article, the basic modules of the classifier are shallow machine learning algorithms. This can be improved by using a more powerful neural network architecture. In the article, all detected unknown attacks are marked as one category. In further studies, the unknown attacks can be clustered and analyzed to further classify the detected unknown attacks. It is worth noting that the number of unknown attacks is only a small part, so it is difficult to classify unknown attacks using cluster analysis. Since training a more powerful neural network requires a lot of data, it is important to investigate how to train a new model when the number of samples belonging to that class is limited.

A Location-Privacy-Aware Taxi-Hailing System: Adaptive Differential Privacy-Based Dynamic Incentive Method

Nowadays location-based service (LBS) has become an important service in people’s daily life. Online taxi-hailing system (DiDi, Uber, etc.) is one of the most common LBS system. As the scale of online taxi services continues to expand, some problems have gradually emerged. Specifically, the uncertainty of taxis and passengers makes it difficult to match them effectively, and the passengers’ location privacy will be threatened from both internal and external of the system. In this paper, we first proposed a Bayesian-based location privacy inference attack method from external adversary’s point of view. After that, an adaptive differential privacy-based dynamic incentive method was proposed. Firstly, an adaptivity clocking area division method was proposed to resist the internal privacy threat. Secondly, a dynamic incentive bidding method was proposed to deal with the trading issue. Thirdly, an exponential-based matching method was proposed to resist the external inference privacy threat. Further, theoretical proofs show that the proposed method satisfy the privacy properties of k-anonymity, 2μ1ε-differential privacy, and the economic properties of incentive compatibility, individual rationality. Finally, the experimental results show that the inference attack would achieve a maximum attack success rate of 95% while ensuring the accuracy within 150 meters, and the proposed adaptive differential privacy-based dynamic incentive method can not only provide a good economic performance in terms of satisfaction ratio, social welfare and travel distance, but also can resist internal privacy threat with less than 1% of privacy leakage probability and reduce the success rate of external privacy inference attacks to 25%.

Serotype 3 Experimental Human Pneumococcal Challenge (EHPC) study protocol: dose ranging and reproducibility in a healthy volunteer population (challenge 3)

IntroductionSince the introduction of pneumococcal conjugate vaccines, pneumococcal disease rates have declined for many vaccine-type serotypes. However, serotype 3 (SPN3) continues to cause significant disease and is identified in colonisation...