David Corlin Marchand, Ioan Manolescu.

Source: Bernoulli, Volume 26, Number 3, 1665--1705.

Abstract:
We study randomly growing trees governed by the affine preferential attachment rule. Starting with a seed tree $S$, vertices are attached one by one, each linked by an edge to a random vertex of the current tree, chosen with a probability proportional to an affine function of its degree. This yields a one-parameter family of preferential attachment trees $(T_{n}^{S})_{ngeq |S|}$, of which the linear model is a particular case. Depending on the choice of the parameter, the power-laws governing the degrees in $T_{n}^{S}$ have different exponents. We study the problem of the asymptotic influence of the seed $S$ on the law of $T_{n}^{S}$. We show that, for any two distinct seeds $S$ and $S'$, the laws of $T_{n}^{S}$ and $T_{n}^{S'}$ remain at uniformly positive total-variation distance as $n$ increases. This is a continuation of Curien et al. ( J. Éc. Polytech. Math. 2 (2015) 1–34), which in turn was inspired by a conjecture of Bubeck et al. ( IEEE Trans. Netw. Sci. Eng. 2 (2015) 30–39). The technique developed here is more robust than previous ones and is likely to help in the study of more general attachment mechanisms.

Thomas Staudt, Timo Aspelmeier, Oskar Laitenberger, Claudia Geisler, Alexander Egner, Axel Munk.

Source: Statistical Science, Volume 35, Number 1, 92--111.

Abstract:
Super-resolution microscopy is rapidly gaining importance as an analytical tool in the life sciences. A compelling feature is the ability to label biological units of interest with fluorescent markers in (living) cells and to observe them with considerably higher resolution than conventional microscopy permits. The images obtained this way, however, lack an absolute intensity scale in terms of numbers of fluorophores observed. In this article, we discuss state of the art methods to count such fluorophores and statistical challenges that come along with it. In particular, we suggest a modeling scheme for time series generated by single-marker-switching (SMS) microscopy that makes it possible to quantify the number of markers in a statistically meaningful manner from the raw data. To this end, we model the entire process of photon generation in the fluorophore, their passage through the microscope, detection and photoelectron amplification in the camera, and extraction of time series from the microscopic images. At the heart of these modeling steps is a careful description of the fluorophore dynamics by a novel hidden Markov model that operates on two timescales (HTMM). Besides the fluorophore number, information about the kinetic transition rates of the fluorophore’s internal states is also inferred during estimation. We comment on computational issues that arise when applying our model to simulated or measured fluorescence traces and illustrate our methodology on simulated data.

Tatiana Stepanova
Apr 1, 2003; 23:2655-2664
Cellular

Zhengui Xia
Sep 1, 1996; 16:5425-5436
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A previously healthy 9-year-old immigrant girl from Mexico was evaluated in the emergency department (ED) with one week of fatigue, fevers, rhinorrhea, and cough. She initially presented to her primary pediatrician, where a complete blood count revealed neutropenia, prompting referral to the ED. In the ED, she was found to be influenza A–positive. Because of dehydration, she received intravenous fluids and was admitted to the pediatric hospital medicine service. After 2 days, influenza symptoms improved, and oral intake increased. However, she was noted to have decreased bilateral lower-extremity strength, absent Achilles reflexes, decreased lower-extremity sensation and proprioception, a positive result on the Romberg sign, and abnormal heel-to-shin testing results. These findings prompted an urgent neurology consultation. After extensive imaging, laboratory evaluation, and further consultations, a diagnosis was established.

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It is not known whether birth at a pediatric cardiac specialty center or at a hospital with a higher neonatal level of care affects mortality for infants with ductal-dependent congenital heart disease.

For infants with ductal-dependent congenital heart disease, there is no difference in 90-day mortality for those born at specialty centers versus other centers in the state of Washington. (Read the full article)

Children with sickle cell disease are at high risk of complications from influenza infection and have been recommended to receive annual influenza vaccine since the 1970s. Few safety studies, however, have examined the safety of influenza vaccine in this population.

This large cohort study did not find an association between influenza vaccination and hospitalization for sickle cell crises in children with sickle cell anemia. (Read the full article)

High-grade vesicoureteral reflux is a risk factor for impaired renal function. Diagnosis by voiding cystourethrography is invasive and highly uncomfortable. As only a minority of children show high-grade vesicoureteral reflux, this exposes the majority to unnecessary distress.

This case-control study proved that high-grade vesicoureteral reflux is identifiable with high sensitivity using urinary proteome analysis, based on capillary electrophoresis coupled to mass spectrometry in a cohort suspected of having vesicoureteral reflux, thus sparing the majority of children from invasive diagnostics. (Read the full article)

Despite recommendations and a universal immunization program, a recent survey reported suboptimal influenza vaccination coverage in children aged 6 to 23 months in Ontario. Little is known about predictors of coverage in young children to target immunization strategies.

Full influenza vaccination coverage in young children in Ontario is <10% and declining since the 2006–2007 season. Medically high-risk children including low birth weight infants are more likely to be immunized, but maternal and health services characteristics remain important. (Read the full article)

Twin studies provide a natural experiment that can determine the extent of genetic and environmental influences on sleep behavior. Previous studies have indicated that genes contribute moderately to sleep.

In the largest pediatric study to date, we demonstrate that the shared environment strongly influences sleep behavior in infants, with no gender differences in the results. This research provides strong impetus to future work identifying the key modifiable environmental drivers. (Read the full article)

A single inhalation of laninamivir octanoate has previously been shown to be as effective as repeated doses of zanamivir in vitro and in vivo, but it is not known whether this is also the case for children.

Median time to fever resolution was not significantly different between laninamivir octanoate and zanamivir for pediatric patients with influenza. The severity of influenza symptoms and the frequency of complications were similar in the 2 groups. (Read the full article)

There is no literature on the concentrations of vitamin B₆ vitamers in cerebrospinal fluid of preterm and term newborn infants. This knowledge, however, is highly important, because vitamin B₆ plays a pivotal role in brain development and functioning.

In cerebrospinal fluid of newborn infants, B₆ vitamer concentrations are strongly dependent on postmenstrual age, indicating that vitamin B₆ homeostasis in brain differs between preterm and term newborns. This has implications for the evaluation of epilepsy and vitamin B₆ deficiency. (Read the full article)

This research presents the first 2 experimental studies on the short-term effects of smoking portrayal in movies on children’s beliefs about smoking.

Exposure to movie smoking from cartoon and family-oriented movies had no effect on implicit associations toward smoking. For smoking beliefs, effects were again small and only statistically significant for social norms regarding smoking. (Read the full article)

The US Surgeon General has determined that the relationship between movie smoking exposure (MSE) and youth smoking is causal; however, it is not known whether movie rating influences how adolescents respond.

The response to PG-13–rated MSE was indistinguishable from R-rated MSE. An R rating for smoking could reduce smoking onset in the United States by 18% (by eliminating PG-13 MSE), an effect similar to making all parents maximally authoritative in their parenting. (Read the full article)

Among adolescents, weight status has been inversely associated with sports participation but not active commuting or physical education. Studies of each form of physical activity have not included adequate adjustments for other physical activities, previous body weight, or diet quality.

Estimates indicate overweight/obesity and obesity prevalence would decrease by 11% and 26%, respectively, if adolescents played on at least 2 sports teams per year; obesity prevalence would decrease by 22% if adolescents walked/biked to school 4–5 days per week. (Read the full article)

Since the introduction of effective vaccines in the United States, the incidence of invasive Haemophilus influenzae type b (Hib) disease in children aged <5 years has decreased by 99%. In 2007, in response to limited vaccine supply, Hib booster doses were deferred for 18 months.

This review found no significant change in the incidence of invasive Hib disease in the United States during the booster dose deferral period, suggesting that booster dose deferral is a reasonable approach to Hib vaccine shortages in the short-term. (Read the full article)

The 2009 influenza A (H1N1) pandemic caused illness in all age groups, but children were disproportionately affected. Children with underlying neurologic disorders were at high risk of influenza-related complications, including death.

This study provides the first detailed description of underlying neurologic disorders among children who died of influenza A (H1N1)pdm09 virus infection. (Read the full article)

Although several studies have demonstrated increased morbidity and mortality with pH1N1 in children, others have found its clinical course to be similar to seasonal influenza. Moreover, most studies were conducted at single centers, thus raising concerns about generalizability of findings.

This analysis provides national-level active hospital-based surveillance data comparing pH1N1 with 5 previous years of seasonal influenza A and demonstrates differences in risk factors and clinical presentation but not in ICU admission or mortality. (Read the full article)

Understanding human disease genomics requires large population-based studies. There is lack of standardization, as well as social and ethical concerns surrounding the consent process for pediatric participation in a biorepository.

The study identifies specific barriers to pediatric participation in biorepositories relative to adults, and proposes strategies to improve ethical and responsible participation of pediatric-aged patients in large-scale genomics and biorepository-driven research without significantly increasing research burden for affected families. (Read the full article)

There are limited data on current testing and treatment patterns for children hospitalized with pneumonia, and on whether institutional guidelines affect care.

The use of institutional clinical practice guidelines was not associated with changes in diagnostic testing, hospital length of stay, or costs for children hospitalized with pneumonia, but was associated with increased use of narrow-spectrum antibiotics. (Read the full article)

Stress in parents has been shown to be related to child obesity.

The presence of multiple parent stressors was related to child obesity, and parent perception of stress was related to child fast-food consumption. Stress in parents may be an important risk factor for child obesity and related behaviors. (Read the full article)

Youth exposure to retail tobacco advertisements and displays is associated with smoking initiation. The Family Smoking Prevention and Tobacco Control Act of 2009 gives states and local governments legal authority to regulate the time, place, and manner of tobacco advertising.

This is the first experimental study using a virtual store environment to provide evidence that a policy banning tobacco product displays at the point of sale may deter youth from attempting to purchase tobacco products at retail stores. (Read the full article)

Influenza is an important cause of medically attended illness in young children before expanding influenza vaccine recommendations for children.

This study characterizes the health care burden of influenza in young children over 5 years (2004–2009) when influenza vaccine recommendations were expanded to all children aged ≥6 months. (Read the full article)

Autism is a disorder that significantly affects language/communication skills, with many children not developing fluent language. The rate of spoken language acquisition after severe language delay and predictors of functional language, beyond comorbid intellectual disability, is less clear.

This study uses the largest sample to date to examine the relationship between key deficits associated with autism and attainment of phrase and/or fluent speech after a severe language delay, providing information to guide therapeutic targets and developmental expectations. (Read the full article)

Medications used to treat gastroesophageal reflux disease (GERD) are some of the most widely used medications in children younger than 1 year. There are strong indications that GERD is overdiagnosed and overtreated.

The factors that drive overtreatment of GERD are not well understood, but it has been proposed that the use of the GERD disease label could perpetuate use of medication. In this study we find evidence for this possibility. (Read the full article)

Yearly influenza immunization is recommended in patients with inflammatory bowel disease (IBD). However, concern regarding vaccine-related adverse events may limit uptake, and case reports in the literature detail disease flares after immunization.

Influenza immunization rates in children with IBD are low but immunization did not result in increased outpatient visits, hospitalizations or emergency visits. Immunization was associated with fewer IBD-related visits in the post-vaccine period, which may indicate protection against IBD symptoms. (Read the full article)

Sleep patterns of adult monozygotic twins are more similar than those of dizygotic twins, showing moderate heritability and little effects of environmental influences. There have been very few genetically informative studies of sleep in preschool children and results appear inconsistent.

From previous studies, we investigated daytime and nighttime continuous sleep duration longitudinally. This is the first time that the etiologies of daytime and nighttime continuous sleep duration trajectories were studied in early childhood. (Read the full article)

The ideal management of children with vesicoureteral reflux (VUR) remains a source of debate. There is little evidence to support many of the current management practices for children with VUR who have had 1 or 2 urinary tract infections.

Baseline associations, including bladder and bowel dysfunction and imaging studies, from the largest randomized, controlled trial conducted to date aimed at assessing the value of antimicrobial prophylaxis in children with urinary tract infection and VUR are presented. (Read the full article)

Stress affects health of children, potentially persisting as a trajectory into adulthood. Earlier biological markers assess only momentary stress, making it difficult to investigate stress over longer periods of time. Cortisol in hair is a new biomarker of prolonged stress.

Mother and child hair cortisol association suggests a heritable part or maternal calibration. Cortisol output gradually stabilizes, has a stable trait, and is positively correlated to birth weight. Hair cortisol is a promising noninvasive biomarker of prolonged stress, especially applicable for children. (Read the full article)

Influenza-associated deaths in children occur every year among children of all ages. Young children and those with high-risk medical conditions are at higher risk of influenza-related complications.

This study describes influenza-associated pediatric deaths over 8 influenza seasons in the United States and compares characteristics of deaths in children with high-risk medical conditions with those in children without high-risk medical conditions. (Read the full article)

Few data on treating children hospitalized for influenza with neuraminidase inhibitors are available, contributing to uncertainty regarding the benefits of treatment.

This study of nearly 800 critically ill children suggests that treatment with neuraminidase inhibitors improves survival from influenza. This message needs additional emphasis, given that in the past 2 seasons over one-third of cases did not receive antiviral treatment. (Read the full article)

Early timing of puberty and affiliation with deviant friends are associated with higher levels of delinquent and aggressive behavior. Early-maturing adolescents tend to affiliate with more-deviant peers and appear more susceptible to negative peer influences.

Young early-maturing girls do not yet associate with deviant friends but are more susceptible to negative peer influences. Early puberty effects are stable over time for delinquency but dissipate for aggression. Most of these relationships are invariant across race/ethnicity. (Read the full article)

The familial nature of vesicoureteral reflux (VUR) is well recognized. Several studies have shown that siblings of children with VUR are at much higher risk for reflux than the general pediatric population with a reported prevalence between 26% and 50%.

There is increased risk of renal cortical abnormalities in siblings with a previous urinary tract infection, siblings with high-grade VUR, and siblings >1 year of age. This information may be useful when counseling parents about the risk of familial VUR. (Read the full article)

In the United States, given the high burden of disease, influenza vaccine is recommended for all children from age 6 months. The paucity of vaccine effectiveness data in children <2 years has led some to argue against routine vaccination in this age group.

This study reveals the effectiveness of trivalent influenza vaccine in young children and supports the current Advisory Committee on Immunization Practices recommendation. This study provides the strongest evidence to date confirming the effectiveness of trivalent influenza vaccine in children <2 years of age. (Read the full article)

Early establishment of a dental home is critical for addressing the "silent epidemic" of early childhood caries. Physicians and dentists have worked to improve children’s access to dental care, but little is known about caregivers’ role in this context.

Addressing factors that affect the establishment of a child’s dental home, such as caregivers’ dental neglect and problem-driven care-seeking behaviors, is essential. Caregiver engagement seems to be pivotal for increasing use of preventive services while decreasing episodic and problem-initiated care. (Read the full article)

Prematurely born infants commonly have abnormal metabolic screens.

Both gestational and chronological age influence metabolic profiles used to screen for inborn errors of metabolism. (Read the full article)

Severe complications, such as respiratory failure, have been described in influenza infection. Clinicians are commonly faced with influenza-like illnesses (ILI), which is the initial nonspecific presentation of many respiratory viruses; the risk of severe complications from ILI are unknown.

Severe complications occurred in children initially presenting with ILI, irrespective of the virus identified. Risk factors for severe complications did not differ by demographics or respiratory virus, although children with high-risk conditions are at greater risk of severe complications. (Read the full article)

Influenza leads to respiratory deteriorations in cystic fibrosis (CF) patients. In children, live attenuated influenza virus vaccine (LAIV) is more efficacious than inactivated influenza vaccines, which could be beneficial for CF. Data on the safety of LAIV in this population are scarce.

This study assesses LAIV’s safety in patients with CF and is necessary to determine whether the anticipated benefits associated with LAIV will outweigh potential risks. This can potentially lead to a recommendation for preferential LAIV use in this population. (Read the full article)

The built environment may affect weight status by presenting opportunities or barriers for exercise and nutritious eating. Although there is substantial cross-sectional evidence linking neighborhood factors and childhood obesity, causal uncertainty remains, owing to conceptual and methodological challenges.

This prospective study examined neighborhood influences on obesity during the transition to adolescence, a sensitive period for excess weight gain. Girls living in neighborhoods characterized by physical disorder or increased access to food and service retailers exhibited higher obesity risk. (Read the full article)

Influenza represents a leading cause of morbidity and a rare cause of death in children. Annual influenza vaccination was gradually expanded to include all children ≥6 months in 2008. The impact of these recommendations on disease burden is unclear.

We assessed the burden of influenza-related health care encounters in children aged 6 to 59 months from 2000 to 2011. In this ecologic exploration, influenza vaccination and influenza-related emergency department visits increased over time, whereas hospitalizations decreased. Influenza-related health care encounters were greater when A(H3N2) circulated. (Read the full article)