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Good quality friendships and relationships are critical to the development of social competence and are associated with quality of life and mental health in childhood and adolescence. Through social distancing and isolation restrictions, the COVID-19 pandemic has had an impact on the way in which youth socialize and communicate with friends, peers, teachers and family on a daily basis. In order to understand children's social functioning during the pandemic, it is essential to gather information on their experiences and perceptions concerning the social changes unique to this period. The objective of this study was to document children and adolescents' perspectives regarding their social life and friendships during the COVID-19 pandemic, through qualitative interviews.Participants (N = 67, 5-14 years) were recruited in May and June 2020. Semi-structured interviews were conducted via a videoconferencing platform. A thematic qualitative analysis was conducted based on the transcribed and coded interviews (NVivo).The upheavals related to the pandemic provoked reflection among the participants according to three main themes, each of which included sub-themes: (1) the irreplaceable nature of friendship, (2) the unsuspected benefits of school for socialization and (3) the limits and possibilities of virtual socialization.The collection of rich, qualitative information on the perspectives of children and adolescents provides a deeper understanding of the consequences of the pandemic on their socialization and psychological health and contributes to our fundamental understanding of social competence in childhood.

Understanding the negative impact of the pandemic on chil-dren and adolescents is essential in order to provide propersupport and intervention. Nonetheless, surmounting adver-sity, such as COVID-19, may also provide positive lessonsfor youth to overcome the negative consequences of thepandemic and prepare society for future crises. The objec-tive of the current qualitative study was to document theperceived positive aspects identified by children and adoles-cents during COVID-19 and how they made sense of theirexperience. Participants (N=67, 5–14 years old) were rec-ruited in May and June 2020. Semi-structured interviewswere conducted via a videoconferencing platform. Based onthe transcribed and coded interviews, a thematic qualitativeanalysis was derived utilizing NVivo. Participants' answerswere grouped into four main themes and sub-themes:(1) school changes, (2) bonding time, (3) free time, and(4) technology usage. Analysing youth perspectives on theirexperience of the COVID-19 pandemic provides insight intosome of the positive changes and lessons that can be gainedamidst the overwhelming negative consequences of the pandemic.

OBJECTIVE To report preliminary empirical data on a novel, developmentally appropriate, observational postconcussive symptoms inventory for infants, toddlers, and preschoolers. SETTING Emergency departments of 2 tertiary, urban pediatric hospitals. PARTICIPANTS Ninety-eight children (0-8 years of age; mean age at injury = 33.00, SD = 24.7 months) with mild traumatic brain injury (concussion) divided into younger (0-2 years) and older (3-8 years) age groups. DESIGN Observational study. MAIN MEASURE The Report of Early Childhood Traumatic Injury Observations & Symptoms (REACTIONS) documents 17 postconcussive symptoms representing observable manifestations thereof and was completed by parents in the acute (24-48 hours; n = 65), subacute (7-14 days; n = 78), and/or persistent phase (25-35 days; n = 72) post-mild traumatic brain injury. RESULTS Different patterns of postconcussive symptoms were reported by age group, with behavioral manifestations particularly salient in younger children. More children younger than 2 years had sleep and comfort-seeking symptoms at each of the 3 postinjury time points. CONCLUSION Postconcussive symptoms may manifest differently after mild traumatic brain injury sustained during early childhood. To fully understand and address their presence and evolution, developmentally sound measures such as the REACTIONS inventory are required.

In order to ensure the safety of vaccines produced on avian cells, rigorous testing for the absence of avian retroviruses must be performed. Current methods used to detect avian retroviruses often exhibit a high invalid-test/false-positive rate, rely on hard-to-secure reagents, and/or have readouts that are difficult to standardize. Herein, we describe the development and validation of two consistent and sensitive methods for the detection of avian retroviruses in vaccines: viral amplification on DF-1 cells followed by immunostaining for the detection of avian leukosis virus (ALV) and viral amplification on DF-1 cells followed by fluorescent product-enhanced reverse transcriptase (F-PERT) for the detection of all avian retroviruses. Both assays share an infectivity stage on DF-1 cells followed by a different endpoint readout depending on the retrovirus to be detected. Validation studies demonstrated a limit of detection of one 50% cell culture infectious dose (CCID 50 )/ml for retrovirus in a 30-ml test inoculum volume for both methods, which was as sensitive as a classical method used in the vaccine industry, namely, viral amplification on primary chicken embryo fibroblasts followed by the complement fixation test for avian leukosis virus (COFAL). Furthermore, viral amplification on DF-1 cells followed by either immunostaining or F-PERT demonstrated a sensitivity that exceeds the regulatory requirements for detection of ALV strains. A head-to-head comparison of the two endpoint methods showed that viral amplification on DF-1 cells followed by F-PERT is a suitable method to be used as a stand-alone test to ensure that vaccine preparations are free from infectious avian retroviruses.

This article develops a model of spread and depth setting under asymmetric information where the equilibrium depth is proportionally more sensitive than the spread to changes in the degree of information asymmetry. The analysis uses a one-period model in which a risk-neutral, monopolistic market maker faces a price-sensitive liquidity trader and a better informed trader who is alternatively risk neutral and risk averse. The equilibrium depth can take values ranging from 0 to infinity, depending on the information asymmetry, the asset volatility, and the strength of the liquidity demand, while the spread remains positive and finite.

When a teenager is diagnosed with a life-threatening condition, priority is given to the provision of care, but the continuation of the adolescent's education is also encouraged, through the hospital school. Thereby, like all children of his age, Issem, suffering from an osteosarcoma, will sit his secondary school exams and will be supported to the end by his teachers. Personal accounts.

The market for U.S. Treasury securities is by many measures the largest, most active debt market in the world, and the securities play a pivotal role in world financial markets. The market has evolved over time in keeping with the changing needs of both the Treasury and investors. After describing the market's structure and examining the factors driving the demand for Treasury securities in some detail, this article discusses recent developments, including the introduction of inflation-indexed securities and a decline in the issuance of Treasury securities.

This paper uses a competitive equilibrium model to study how institutional investors influence the volatility and the informativeness of asset prices. Institutional investors are assumed to be "rational" informed traders, while individual investors are supposed to be "naive" informed traders, insofar as the former use the equilibrium price to extract information while the latter do not. The paper compares the informativeness and the volatility of the equilibrium price in an economy in which the informed traders are naive and in one where they are rational; the paper also investigates how the price characteristics react to changes in the parameters, in particular in the number of informed traders.

This paper shows how to extract information from equilibrium trading volume. The analysis is first carried out in a market- clearing framework with symmetrically (and later normally) distributed demands, and is then extended to include market-making models. The conclusions of this paper hence apply to the majority of the models developed in the noisy rational expectations literature. If a random variable is symmetrically distributed with the traders' demands around zero and the asset market clears, the volume-based conditional distribution of this variable is symmetric, and consequently its conditional expectation based on volume is zero. The random variable under consideration may be the true value of the asset, the price or, in a dynamic model, the price difference. The paper further proves that the covariance between the absolute value of any variable jointly normally distributed with the traders' demands and the equilibrium volume is positive, which agrees with the empirical evidence of a positive covariance between the absolute value of the price difference and volume. Furthermore, numerical examples indicate that, when the asset value is jointly normally distributed with the traders' demands, the probability ofextreme realizations for the asset true value conditioned on volume is increasing in volume. The paper's proposition hold in market-making frameworks as long as the price, the asset value and the traders' demands are symmetrically (resp. jointly normally) distributed. Finally, the paper develops a simple static model where transaction costs can induce a positive covariance between price and volume.

This paper investigates the relations between aggregate trading volume and information on financial markets from a theoretical standpoint. Through numerical examples, it relates some statistics describing equilibrium price and volume--such as the variance of the price and its correlation with the true asset value, the volume mean, variance, skewness, and kurtosis--to the distribution of information across traders. The analysis is carried out in a static noisy rational expectations framework, with multiple informed traders, where both the precision and the correlation of the signals observed by the traders can be modified.

Le titre initialement choisi pour la revue etait Seve, pour « Sante, enjeux, visions, equilibres », et l’ambition de permettre de partager ce que Victor Hugo appelait « la seve intellectuelle de la societe », comme le rappelait Didier Tabuteau dans l’editorial du premier numero. Si, en dix ans, le titre a change, l’ambition n’a pas varie ! Le contexte economique et intellectuel, lui, n’est guere favorable a une revue de reflexion et de prospective ; cependant l’une et l’autre nous semblent plus que jamais necessaires.Cet anniversaire est donc l’occasion de jeter un regard en arriere et de mesurer le chemin parcouru. On trouvera ici, rassemble sous les quatre termes fondamentaux qui organisent la reflexion editoriale, un choix, forcement subjectif, d’extraits d’articles particulierement pertinents. On mesurera egalement combien l’essentiel des propos reste particulierement actuel...

A new biomaterial made from human placental collagen type IV has been developed in corneal inlays for refractive keratoplasty. Eight dogs received intracorneal lenses to investigate biocompatibility. Postoperative follow-up observation of 2 years revealed that the eyes remained clear and without inflammatory reaction. Endothelial cells were unaltered. Histological and ultrastructural studies showed no signs of inflammation, ulceration, or encapsulation. No fibroblastic activity was evident at the lens stroma interface.