Optimal and worst examination strategies for COVID-19

Coronavirus disease 2019 (COVID-19) is an emerging threat to the whole world, and every government is seeking an optimal solution. However, none of them have succeeded, and they have only provided series of natural experiments. Although simulation studies seem to be helpful, there is no model that addresses the how much testing to be conducted to minimise the emerging infectious disease outbreaks. In this study, we develop a testing susceptible, infectious, exposed, recovered, and dead (testing-SEIRD) model using two discrete populations inside and outside hospitals. The populations that tested positive were isolated. Through the simulations, we examined the infectious spread represented by the number of cumulative deaths, hospitalisations, and positive tests, depending on examination strategies, testing characteristics, and hospitalisation capacity. We found all-or-none responses of either expansion or extinction of the infectious spreads, depending on the rates of follow-up and mass testing, which represent testing the people identified as close contacts with infected patients using follow-up surveys and people with symptoms, respectively. We also demonstrated that there were optimal and worst examination strategies, which were determined by the total resources and testing costs. The testing-SEIRD model is useful in making decisions on examination strategies for the emerging infectious disease outbreaks.

Natural Entrapments of Killer Whales (Orcinus orca): A Review of Cases and Assessment of Intervention Techniques

Identifying mortality sources and mitigation solutions is crucial in species management and conservation. In killer whales (Orcinus orca), mortality events may pose a serious concern for the conservation of small discrete populations, especially if they involve entire groups. This study investigated 19 incidents involving 116 killer whales from a minimum of five populations becoming naturally entrapped in inshore areas of the North Pacific (n = 12) and North Atlantic (n = 7) oceans between 1949 and 2019. Here, we aim to provide an assessment of possible causal factors, lethality and human responses to these events. Site characteristics and group size identified three categories of entrapments. In Category 1, nine cases involved small groups of killer whales (median = 5, range: 1–9) at sites characterized by severe geographic and food constraints. Four cases in Category 2 included larger groups (median= 14, range: 6–19) and entrapment sites with no obvious geographic constraints but at which man-made structures could have acted as deterrents. Five cases assigned to Category 3 involved lone, often young individuals settling in a restricted home range and engaging in interactions with people and boats. Overall, all or some of the killer whales swam out on their own after a mean of 36 d of entrapment (range: 1–172, SD = 51, n = 9 cases), died of nutritional/physiological stress after 58 d (range: 42–90, SD = 21, n = 3 cases) or of injury after ~5 years of daily interactions with boat traffic (n = 1 case). Indication of the killer whales' declining condition or being at risk of injury, and of poor habitat quality, led to the decision to intervene in seven cases where a variety of methods were used to guide or relocate remaining individuals back to open waters after 39 d (SD = 51, range = 8–150). Monitoring protocols, which aided in identifying entrapment situations, and intervention methods which enhanced the health and survival of entrapped killer whales, are discussed.

Modelling complex population structure using F-statistics and Principal Component Analysis

Human genetic diversity is shaped by our complex history. Population genetic tools to understand this variation can broadly be classified into data-driven methods such as Principal Component Analysis (PCA), and model-based approaches such as F -statistics. Here, I show that these two perspectives are closely related, and I derive explicit connections between the two approaches. I show that F-statistics have a simple geometrical interpretation in the context of PCA, and that orthogonal projections are the key concept to establish this link. I illustrate my results on two examples, one of local, and one of global human diversity. In both examples, I find that population structure is sparse, and only a few components contribute to most statistics. Based on these results, I develop novel visualizations that allow for investigating specific hypotheses, checking the assumptions of more sophisticated models. My results extend F-statistics to non-discrete populations, moving towards more complete and less biased descriptions of human genetic variation.

Texas sheriffs’ perceptions on firearm regulations and mass shootings

Criminal justice research often focuses exclusively on municipal police departments. Sheriffs’ departments are largely ignored in this research despite this population’s reach and role. There are nearly 3,000 sheriffs’ offices around the United States and they often serve as the only law enforcement body in rural areas. This study sought to address the scarcity of this research and focused on Texas sheriffs’ views regarding firearm regulations and the causes of mass shootings. An 18-question instrument created in consult with the Texas Narcotic Officers Association was sent to each sheriff in the 254 counties of Texas to assess their perceptions regarding solutions to mass shootings, disqualification criteria for gun ownership, and civilian access to certain types of firearms and ammunition. Responding sheriffs, as a whole, were reluctant to limit access to guns and ammunition as a general matter, but strongly agreed that certain discrete populations should have limited or no access to firearms. Policy implications are discussed.

The alx3 gene shapes the zebrafish neurocranium by regulating frontonasal neural crest cell differentiation timing

ABSTRACT During craniofacial development, different populations of cartilage- and bone-forming cells develop in precise locations in the head. Most of these cells are derived from pluripotent cranial neural crest cells and differentiate with distinct developmental timing and cellular morphologies. The mechanisms that divide neural crest cells into discrete populations are not fully understood. Here, we use single-cell RNA sequencing to transcriptomically define different populations of cranial neural crest cells. We discovered that the gene family encoding the Alx transcription factors is enriched in the frontonasal population of neural crest cells. Genetic mutant analyses indicate that alx3 functions to regulate the distinct differentiation timing and cellular morphologies among frontonasal neural crest cell subpopulations. This study furthers our understanding of how genes controlling developmental timing shape craniofacial skeletal elements.

Molecular identification of Brachygenys and Haemulon species (Perciformes: Haemulidae) from the Brazilian coast

The fishes of the Haemulidae family are currently allocated to 19 genera with a worldwide distribution in the tropical and subtropical waters of the world’s oceans. Brachygenys and Haemulon are important genera of reef fish in Brazil, as they occur in large shoals, which are both ecologically and commercially valuable. This study identified the Brazilian species of the genera Brachygenys and Haemulon using DNA barcodes. While we found only a single lineage in Brachygenys chrysargyrea, Haemulon melanurum, H. parra, and H. squamipinna, more than one molecular operational taxonomic unit (MOTU) was identified in H. atlanticus, H. aurolineatum, and H. plumieri, indicating the possible existence of discrete populations or cryptic species.

The ‘migratory connectivity’ concept, and its applicability to insect migrants

Migratory connectivity describes the degree of linkage between different parts of an animal’s migratory range due to the movement trajectories of individuals. High connectivity occurs when individuals from one particular part of the migratory range move almost exclusively to another localized part of the migratory range with little mixing with individuals from other regions. Conversely, low migratory connectivity describes the situation where individuals spread over a wide area during migration and experience a large degree of mixing with individuals from elsewhere. The migratory connectivity concept is frequently applied to vertebrate migrants (especially birds), and it is highly relevant to conservation and management of populations. However, it is rarely employed in the insect migration literature, largely because much less is known about the migration circuits of most migratory insects than is known about birds. In this review, we discuss the applicability of the migratory connectivity concept to long-range insect migrations. In contrast to birds, insect migration circuits typically comprise multigenerational movements of geographically unstructured (non-discrete) populations between broad latitudinal zones. Also, compared to the faster-flying birds, the lower degree of control over movement directions would also tend to reduce connectivity in many insect migrants. Nonetheless, after taking account of these differences, we argue that the migratory connectivity framework can still be applied to insects, and we go on to consider postulated levels of connectivity in some of the most intensively studied insect migrants. We conclude that a greater understanding of insect migratory connectivity would be of value for conserving threatened species and managing pests.

Skin Immunology and Rejection in VCA and Organ Transplantation

Purpose of Review Skin provides a window into the health of an individual. Using transplanted skin as a monitor can provide a powerful tool for surveillance of rejection in a transplant. The purpose of this review is to provide relevant background to the role of skin in vascularized transplantation medicine. Recent Findings Discrete populations of T memory cells provide distributed immune protection in skin, and cycle between skin, lymph nodes, and blood. Skin-resident TREG cells proliferate in response to inflammation and contribute to long-term VCA survival in small animal models. Early clinical studies show sentinel flap rejection to correlate well with facial VCA skin rejection, and abdominal wall rejection demonstrates concordance with visceral rejection, but further studies are required. Summary This review focuses on the immunology of skin, skin rejection in vascularized composite allografts, and the recent advances in monitoring the health of transplanted tissues using distant “sentinel” flaps.