We examine the effect of high-frequency trading on market quality from the perspective of a limit order trader. By competing with slower limit order traders, high-frequency traders impose a welfare ...externality by selectively crowding out the most profitable limit orders. The order book imbalance immediately before each order submission, cancellation, and trade suggests that high-frequency traders strategically use limit order book information to supply liquidity on the thick side of the order book and demand liquidity from the thin side. This strategic behavior is more pronounced during volatile periods and when trading speeds increase.
This paper was accepted by Bruno Biais, finance.
Funding:
This work was supported by the Centre for International Finance and Regulation Grant T013.
Supplemental Material:
The online appendix and data are available at
https://doi.org/10.1287/mnsc.2022.4539
.
Determining the epigenetic program that generates unique cell types in the kidney is critical for understanding cell-type heterogeneity during tissue homeostasis and injury response. Here, we profile ...open chromatin and gene expression in developing and adult mouse kidneys at single cell resolution. We show critical reliance of gene expression on distal regulatory elements (enhancers). We reveal key cell type-specific transcription factors and major gene-regulatory circuits for kidney cells. Dynamic chromatin and expression changes during nephron progenitor differentiation demonstrates that podocyte commitment occurs early and is associated with sustained Foxl1 expression. Renal tubule cells follow a more complex differentiation, where Hfn4a is associated with proximal and Tfap2b with distal fate. Mapping single nucleotide variants associated with human kidney disease implicates critical cell types, developmental stages, genes, and regulatory mechanisms. The single cell multi-omics atlas reveals key chromatin remodeling events and gene expression dynamics associated with kidney development.
Over the past several decades there have been dramatic shifts in demographic patterns pertaining to family formation, with declining and delayed marriage and childbearing, and increased cohabitation ...in the United States and other Western industrialized nations. These trends in family demography have been predominantly studied using large-scale datasets, which have identified total population and subgroup trends over time, including differences by age, gender, racial/ethnic, economic, educational, religious, and other characteristics. However, there is limited knowledge and understanding of how individuals across different levels of social position, as well as other important characteristics, make decisions around forming families. This lack of qualitative data on contemporary attitudes regarding family formation has hampered our ability to more completely understand the factors driving behaviors pertaining to the large-scale (ie, international) shifts in demographic trends. The Social Position and Family Formation (SPAFF) project is an in-depth interview study that used quantitative data to guide recruitment of a large sample for qualitative interview data collection on factors influencing different aspects of family formation among heterosexual females and males (18-35 years) in the context of individuals' social position. This methodological paper describes the use of a 'quantitatively-informed' purposive sampling approach in a large metropolitan area to collect qualitative data (through in-depth interviews) from a large sample (n = 200), utilizing web-based tools for successful community-based recruitment and project management.
Much research is being carried out using publicly available Twitter data in the field of public health, but the types of research questions that these data are being used to answer and the extent to ...which these projects require ethical oversight are not clear.
This review describes the current state of public health research using Twitter data in terms of methods and research questions, geographic focus, and ethical considerations including obtaining informed consent from Twitter handlers.
We implemented a systematic review, following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, of articles published between January 2006 and October 31, 2019, using Twitter data in secondary analyses for public health research, which were found using standardized search criteria on SocINDEX, PsycINFO, and PubMed. Studies were excluded when using Twitter for primary data collection, such as for study recruitment or as part of a dissemination intervention.
We identified 367 articles that met eligibility criteria. Infectious disease (n=80, 22%) and substance use (n=66, 18%) were the most common topics for these studies, and sentiment mining (n=227, 62%), surveillance (n=224, 61%), and thematic exploration (n=217, 59%) were the most common methodologies employed. Approximately one-third of articles had a global or worldwide geographic focus; another one-third focused on the United States. The majority (n=222, 60%) of articles used a native Twitter application programming interface, and a significant amount of the remainder (n=102, 28%) used a third-party application programming interface. Only one-third (n=119, 32%) of studies sought ethical approval from an institutional review board, while 17% of them (n=62) included identifying information on Twitter users or tweets and 36% of them (n=131) attempted to anonymize identifiers. Most studies (n=272, 79%) included a discussion on the validity of the measures and reliability of coding (70% for interreliability of human coding and 70% for computer algorithm checks), but less attention was paid to the sampling frame, and what underlying population the sample represented.
Twitter data may be useful in public health research, given its access to publicly available information. However, studies should exercise greater caution in considering the data sources, accession method, and external validity of the sampling frame. Further, an ethical framework is necessary to help guide future research in this area, especially when individual, identifiable Twitter users and tweets are shared and discussed.
PROSPERO CRD42020148170; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=148170.
Emerging and re-emerging viral diseases have increased in number and geographical extent during the last decades. Examples include the current COVID-19 pandemic and the recent epidemics of the ...Chikungunya, Ebola, and Zika viruses. Immune responses to viruses have been well-characterised within the innate and adaptive immunity pathways with the outcome following viral infection predominantly attributed to properties of the virus and circumstances of the infection. Perhaps the belief that the immune system is often considered as a reactive component of host defence, springing into action when a threat is detected, has contributed to a poorer understanding of the inherent differences in an individual's immune system in the absence of any pathology. In this review, we focus on how these host factors (age, ethnicity, underlying pathologies) may skew the T helper cell response, thereby influencing the outcome following viral infection but also whether we can use these inherent biases to predict patients at risk of a deviant response and apply strategies to avoid or overcome them.
Background: Cervical cancer is one of the most common cancers in women and about 90% of cervical cancer can be reduced by regular screening. The Pap smear has been well in place as a primary cervical ...screening method since 1950s; however, coverage is still not optimal. This study explored the feasibility of HPV self-sampling in two under-screened population groups in Hong Kong (HK): never screened and not regularly screened females, to estimate the uptake rate and preference rate in the future. Materials and Methods: This was a cross-sectional study to explore the acceptability and feasibility of HPV self-sampling in two age groups: aged 25–35 and aged ≥45, which were reported as the highest proportion of the under-screened population in HK between 2017 and 2018. The study invited eligible women from an HPV study cohort to perform HPV self-sampling at home by themselves. The number of specimens returned from participants was recorded and used to determine the feasibility of HPV self-sampling in the community. The participants were asked to fill in the questionnaires before and after HPV self-sampling to indicate their attitudes, acceptability, and future preference for HPV self-sampling as an acceptable alternative primary cervical cancer screening method. Results: A total of 177 subjects participated in the present study and have achieved a good overall uptake rate of 73% (129/177) who returned the self-collected cervicovaginal sample for HPV testing. Among the under-screened population, there was a higher response rate in aged ≥45 than those aged 25–35. The findings also revealed that women who were under-screened, including those who have never been screened, were more likely to prefer HPV self-sampling than those who had regular screening. This study found that the acceptability of HPV self-sampling was fairly positive among the respondents. The findings also indicated that HPV self-sampling was not only beneficial to enhance their health awareness but also to promote the cervical cancer screening uptake rate, especially among the under-screened or never screened populations. Conclusions: HPV self-sampling would be a solution to overcome the perceived barriers in clinician-based screening. The findings also indicated that it could be feasible to use as an alternative primary cervical cancer screening.
Medical curricula include advocacy competencies, but how much physicians engage in advocacy and what enables this engagement is not well characterized. The authors assessed facilitators and barriers ...to advocacy identified by physician alumni of a reproductive health advocacy training program.
The authors present secondary results from a mixed methods program evaluation from 2018 to 2020, using alumni data from a cross-sectional survey (n = 231) and in-depth interviews (IDIs, n = 36). The survey measured engagement in policy, media, professional organization, and medical education advocacy and the value placed on the community fostered by the program (eight questions, Cronbach's alpha = 0.81). The authors estimated the association of community value score with advocacy engagement using multivariable Poisson regression to estimate prevalence ratios and analyzed IDI data inductively.
Over one third of alumni were highly engaged in legislative policy (n = 90, 39%), professional organizations (n = 98, 42%), or medical education (n = 89, 39%), with fewer highly active in media-based advocacy (n = 54, 23%) in the year prior to the survey. Survey and IDI data demonstrated that passion, sense of urgency, confidence in skills, and the program's emphasis on different forms of advocacy facilitated engagement in advocacy, while insufficient time, safety concerns, and sense of effort redundancies were barriers. The program community was also an important facilitator, especially for "out loud" efforts and for those working in environments perceived as hostile to abortion care (e.g., alumni in hostile environments with high community value scores were 1.8 times 95% CI 1.3, 2.6 as likely to report medium/high levels of media advocacy compared to those with low scores after adjusting for age, gender, and clinical specialty).
Physician advocacy training curricula should include both skills- and community-building and identify a full range of forms of advocacy. Community-building is especially important for physician advocacy for reproductive health services such as abortion care.
To assess the risks of second malignancy and early menopause in a large cohort of patients with gestational trophoblastic tumor who were treated with chemotherapy.
A survey of patients treated at ...Charing Cross Hospital between 1958 and 2000 was performed in 2006 to assemble incidence data for subsequent malignancies and the age at menopause. Treatment records were reviewed for the regimens and durations, and the incidence of subsequent malignancies was compared with that in the national age-matched population.
Data were obtained for 1,903 patients, with a mean follow-up of 16.9 years. Eighty-six patients developed a subsequent malignancy compared with an expected number of 79 (standardized incidence ratio SIR, 1.1; 95% CI, 0.9 to 1.3). The overall risk was low for patients treated with single-agent methotrexate and folinic acid (MTX-FA; SIR, 0.7; 95% CI, 0.5 to 1.1) and also for patients treated with etoposide, methotrexate, and dactinomycin followed by cyclophosphamide and vincristine on alternating weeks (EMA-CO) with an SIR of 0.9 (95% CI, 0.4 to 2.2), but there were significantly increased risks of oral cancer, melanoma, meningioma, and leukemia. The cumulative risk of early menopause was low after MTX-FA but was substantial after EMA-CO, reaching 13% by age 40 years and 36% by age 45 years.
Subsequent cancer risks for patients cured of gestational trophoblastic tumors with modern chemotherapy appear similar to those of the normal population with no overall increased risk of malignancy after MTX-FA or EMA-CO. However, there was evidence of an increased risk of leukemia after EMA-CO and some evidence of other site-specific increased risks based on small patient numbers. All major treatments except MTX-FA increased the risk of early menopause.
Empowerment of control and choice of the service users in health and social care has been incorporated into service provision in various countries. This study aimed to elicit the preference of ...community-based long-term care (LTC) service users on levels of flexibility in service provision. A discrete choice experiment was performed among older community care service users to measure their preference for attributes of LTC services identified from a prior qualitative study. Each participant was asked to make choices in six choice tasks with two alternatives of hypothetical LTC services that were generated from the attributes. A generalized multinomial logistic model was applied to determine the relative importance and willingness to pay for the attributes. It found that the participants preferred multiple flexible providers, determining services by themselves, meeting case managers every month and social workers as sources of information on service provision. Significant preference heterogeneity was found for flexibility in providers and flexibility in services between those with and without activity of daily living impairment. The findings highlighted the preference of older adults for greater flexibility in LTC, while they rely heavily on social workers in decision making. The enhancement of flexibility in LTC should be supported by policies that allow the older service users to make decisions based on their own preferences or communication with social workers instead of determining the services and providers for them. Options should be offered to users to decide their preferred level of flexibility to better reflect their divided preferences.
Hookworms, parasitic nematodes that infect nearly one billion people worldwide, are a major cause of anemia and malnutrition. We hypothesize that hookworms actively manipulate the host immune ...response through the production of specific molecules designed to facilitate infection by larval stages and adult worm survival within the intestine. A full-length cDNA encoding a secreted orthologue of the human cytokine, Macrophage Migration Inhibitory Factor (MIF) has been cloned from the hookworm Ancylostoma ceylanicum. Elucidation of the three-dimensional crystal structure of recombinant AceMIF (rAceMIF) revealed an overall structural homology with significant differences in the tautomerase sites of the human and hookworm proteins. The relative bioactivities of human and hookworm MIF proteins were compared using in vitro assays of tautomerase activity, macrophage migration, and binding to MIF receptor CD74. The activity of rAceMIF was not inhibited by the ligand ISO-1, which was previously determined to be an inhibitor of the catalytic site of human MIF. These data define unique immunological, structural, and functional characteristics of AceMIF, thereby establishing the potential for selectively inhibiting the hookworm cytokine as a means of reducing parasite survival and disease pathogenesis.
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