Mikael Escobar-Bach, Yuri Goegebeur, Armelle Guillou.

Source: Electronic Journal of Statistics, Volume 14, Number 1, 1773--1795.

Abstract:
We consider bias-corrected estimation of the stable tail dependence function in the regression context. To this aim, we first estimate the bias of a smoothed estimator of the stable tail dependence function, and then we subtract it from the estimator. The weak convergence, as a stochastic process, of the resulting asymptotically unbiased estimator of the conditional stable tail dependence function, correctly normalized, is established under mild assumptions, the covariate argument being fixed. The finite sample behaviour of our asymptotically unbiased estimator is then illustrated on a simulation study and compared to two alternatives, which are not bias corrected. Finally, our methodology is applied to a dataset of air pollution measurements.

Anja Janßen, Phyllis Wan.

Source: Electronic Journal of Statistics, Volume 14, Number 1, 1211--1233.

Abstract:
The $k$-means clustering algorithm and its variant, the spherical $k$-means clustering, are among the most important and popular methods in unsupervised learning and pattern detection. In this paper, we explore how the spherical $k$-means algorithm can be applied in the analysis of only the extremal observations from a data set. By making use of multivariate extreme value analysis we show how it can be adopted to find “prototypes” of extremal dependence and derive a consistency result for our suggested estimator. In the special case of max-linear models we show furthermore that our procedure provides an alternative way of statistical inference for this class of models. Finally, we provide data examples which show that our method is able to find relevant patterns in extremal observations and allows us to classify extremal events.

Catherine Orr
Mar 6, 2019; 39:1817-1827
BehavioralSystemsCognitive

Rumored to withstand the weight of a full grown man, their spines have now been studied in unprecedented detail

Bank of England Working Papers by Nicola Garbarino and Benjamin Guin

If you're willing to pay the (necessarily) big bucks to create a new TRX40-based Threadripper desktop, few motherboards on any platform can match the Asus ROG Zenith II Extreme for sheer robustness and feature set.

Extreme Leadership Training camps create unity in Ukraine.

Dell's Latitude 7220 Rugged Extreme Tablet lives up to its name by laughing at drops, splashes, and temperatures that would blow the average slate to smithereens. It's ideal for first responders and factory floors.

Extreme preterm birth is associated with developmental shortcomings that may reduce exercise capacity and participation in physical activities in later life. The number of studies addressing these issues in adolescent populations is limited, test methods differ, and results are diverging.

Exercise capacity after preterm birth was in the same range as in term-born control subjects. Participation in physical activity was lower in preterm subjects compared with control subjects; however, the response to exercise in terms of increased aerobic capacity was similar. (Read the full article)

Pulmonary hypertension is associated with bronchopulmonary dysplasia in extremely low birth weight infants and contributes to morbidity and mortality.

Pulmonary hypertension affects at least 1 in 6 extremely low birth weight infants and persists to discharge in most survivors. Routine screening of these infants with echocardiography at 4 weeks of age identifies only one-third of those affected. (Read the full article)

Among extremely premature infants, survival has improved, but the rate of cognitive impairment has not. Impaired cognition is the most frequent developmental problem identified in survivors. Several antenatal factors have been associated with cognitive impairment, mostly related to social disadvantage.

In addition to social disadvantage, antenatal characteristics associated with cognitive impairment include maternal obesity and thrombosis of fetal stem vessels. Prenatal infection and inflammation were not associated with impaired early cognitive function among extremely preterm infants. (Read the full article)

The demographics of trials that use antenatal consent may not be representative of the populations that they are intended to study.

This study analyzes the difference in clinical outcomes between the enrolled and eligible but not enrolled populations of a trial that required antenatal consent. (Read the full article)

Subjects born preterm have higher blood pressure (BP) in childhood and adolescence. Little is known about at what age the deviation from normal BP starts, and data are especially scarce for the new generation of survivors after extremely preterm birth.

In a population-based study, we found that BP was higher in 2.5-year-old children born extremely preterm compared with controls. This finding might have implications for follow-up programs after preterm birth, with the goal of improving later cardiovascular health. (Read the full article)

Previous cohorts of extremely low birth weight adolescents have assessed their health status similar to that of normal birth weight controls.

Extremely low birth weight adolescents born in the 1990s assess their health similar to controls but report less risk taking. Extremely low and normal birth weight children rate their health to be poorer at 8 than at 14 years. (Read the full article)

Death or neurodevelopmental impairment in extremely premature neonates can be predicted at birth by considering gender, antenatal steroids, multiple birth, birth weight, and gestational age.

Prediction of death or neurodevelopmental impairment in extremely premature infants is improved by using information available later during the clinical course. The importance of birth weight declines, whereas that of respiratory illness severity increases with advancing postnatal age. (Read the full article)

Children born at very low birth weights have significant catch-up weight gain but differences in height remain. Their BMI, however, tends not to be higher than expected. Data are lacking regarding representative cohorts, defined by gestation and compared with contemporaneous controls.

In a geographic cohort of extremely preterm participants followed until age 18, compared with term controls, weight differences diminish over time, and height differences persist. BMI at age 18 is similar. Height at age 2 is a better predictor of final height than midparental height. (Read the full article)

Isolated case reports of abnormal voice after extremely preterm birth are well described; however, there are no systematic studies of long-term voice outcomes in children born preterm.

Significant voice abnormalities were found in more than half of tested children born before 25 weeks’ gestation. Multivariable analyses showed that the number of intubations, not the duration of intubation, and female gender were strongly associated with this adverse outcome. (Read the full article)

Although it is known that extremely preterm children are at increased risk for cognitive deficits, academic underachievement, and behavioral problems, the frequency and severity of these impairments may decline with advances in neonatal care.

Despite recent changes in obstetric and neonatal management of extremely preterm infants, the rate of neurobehavioral impairments at school age is still too high. (Read the full article)

Infant and neonatal mortality rates in the United States decreased markedly during the twentieth century but have not decreased notably during recent years. There has been an increase in preterm and low birth weight births in recent years.

The lack of decrease in infant and neonatal mortality rates in recent years is due in large part to the increasing proportion of preterm and low birth weight infants, particularly infants <500 g. (Read the full article)

Extremely preterm infants who receive antihypotensive therapy have worse outcomes than untreated infants. The reasons for this are not clear. High-quality randomized trials have not been performed to date because of logistical challenges, thereby necessitating alternative methods of investigation.

Antihypotensive therapy administration was not associated with improved in-hospital outcomes for any of the 15 definitions of low blood pressure investigated. Alternative methods of deciding who to treat are needed to maximize patient benefit and minimize harm. (Read the full article)

Significant variation in the mortality of preterm infants has been observed among NICUs. Factors explaining this variation have been difficult to identify.

Sizable center differences in mortality exist, even among similarly sized NICUs in academic centers. Patient characteristics and center treatment rates explain some of the center effect, especially for the youngest infants, but a significant portion of these differences remains unexplained. (Read the full article)

Data available before the 1990s in addition to small studies with clinical populations have shown that ocular growth and development differ between extremely preterm and term-born children.

Contemporary data on long-term visual outcomes indicate that adolescents born extremely low birth weight and/or extremely preterm exhibit more visual sensory and perceptual morbidity than adolescents born at term. (Read the full article)

Extremely preterm infants are at high risk of neonatal mortality or morbidities. Existing prediction models focus on mortality, specific morbidities, or composite mortality and morbidity outcomes and ignore differences in outcome severity.

A simple and practical statistical model was developed that can be applied on the first day after NICU admission to predict outcome severity spanning from no morbidity to mortality. The model is highly discriminative (C-statistic = 90%) and internally valid. (Read the full article)

Cranial ultrasound is routinely used in identifying cerebral abnormalities in premature infants. Grade III and IV intraventricular hemorrhages, cystic periventricular leukomalacia, and late ventriculomegaly are all known predictors of adverse neurodevelopmental sequelae in these infants.

We reviewed neurodevelopmental outcomes among 2414 extreme preterm infants. Infants with grades I and II intraventricular hemorrhage had increased rates of neurosensory impairment, developmental delay, cerebral palsy, and deafness at 2 to 3 years’ corrected age. (Read the full article)

For newborn infants, extreme hyperbilirubinemia (≥24.5 mg/dL) is associated with risk for severe bilirubin encephalopathy. The causal factor of extreme hyperbilirubinemia is often not established. The genotype of Gilbert syndrome, the UGT1A1*28 allele, is considered a potential risk factor.

The UGT1A1*28 allele was not associated with risk for developing extreme hyperbilirubinemia. (Read the full article)

Prophylactic indomethacin in extremely low birth weight infants decreases severe intraventricular hemorrhage and patent ductus arteriosus but it is unknown whether concurrent enteral feeding and prophylactic indomethacin is associated with increased risk of spontaneous intestinal perforation.

The combination of prophylactic indomethacin and enteral feeding during the first 3 days after birth does not increase the risk of spontaneous intestinal perforation. (Read the full article)

White matter abnormality (WMA) on neuroimaging is considered a crucial link with adverse neurodevelopmental outcome in preterm infants. Brain MRI is more sensitive in detecting WMA than cranial ultrasound (CUS), but questions remain about timing and prognostic value of modalities.

Near-term CUS and MRI abnormalities were associated with adverse 18- to 22-month outcomes, independent of early CUS and other factors, underscoring the relative prognostic value of later neuroimaging in this large, extremely preterm cohort surviving to near-term. (Read the full article)

Immune-related bioactive proteins are highly concentrated in the colostrum of mothers who deliver preterm infants. Oropharyngeal administration was proposed as a safe and feasible alternative method of providing colostrum to immunocompromised premature infants.

Oropharyngeally administered colostrum during the first few days of life increased urinary secretory immunoglobulin A and lactoferrin, decreased urinary interleukin-1β, reduced salivary transforming growth factor-β1 and interleukin-8, and reduced the occurrence of clinical sepsis in extremely premature infants. (Read the full article)

Little is known about the mental health of extremely low birth weight survivors in their 30s. It is also unclear whether being born small for gestational age or being exposed to antenatal corticosteroids increases risk in this group.

In their 30s, extremely low birth weight survivors are less likely to have substance problems but are at elevated risk for other psychiatric disorders. Those born small for gestational age are at higher risk, but those exposed to antenatal corticosteroids are at the greatest risk of all. (Read the full article)

Considerable differences in outcome after extremely preterm birth have been reported between centers and regions providing a comparative level of care, but the reasons for these variations have been poorly examined.

In extremely preterm fetuses alive at the mother’s admission for delivery, and in infants born alive, mortality up to 2.5 years is reduced in regions with a more active use of perinatal interventions without increased neurodevelopmental morbidity. (Read the full article)

Infants born extremely premature and infants born to adolescent mothers are at risk for adverse developmental and behavior outcomes. There is limited research on the dual risk imparted to infants born extremely premature to adolescent mothers.

Extremely premature infants of adolescent mothers have significantly increased rates of behavior problems. Nonwhite race and living in ≥3 places by 18 to 22 months of age are risk factors for adverse behavior outcomes among infants of adolescent mothers. (Read the full article)

Studies on the risk of mortality and morbidities of extremely preterm infants of multiple gestation births have shown inconsistent results. Perinatal antecedents, admission status and severity of illness after birth can adversely affect outcomes of the extremely premature infants.

Preterm multiple gestation infants have increased risk of mortality but similar risk of major morbidities compared with singletons. Outcomes improved over time and all adverse outcomes, including mortality, were comparable between multiples and singletons in the most recent 5-year epoch. (Read the full article)

Wolfgang Lindner
May 1, 1999; 103:961-967
ARTICLES

Maureen Hack
Aug 1, 2005; 116:333-341
ARTICLES

C. Michael Cotten
Jan 1, 2009; 123:58-66
ARTICLES

Richard A. Ehrenkranz
Apr 1, 2006; 117:1253-1261
ARTICLES

Betty R. Vohr
Jun 1, 2000; 105:1216-1226
ARTICLES

Barbara J. Stoll
Sep 1, 2010; 126:443-456
ARTICLES

Thaddeus Lorenz, senior in information science and technology, wasn’t always sure what his academic path would be. After starting at Penn State in the Division of Undergraduate Studies, he took some classes centered on one of his passions: coding. Then, he decided to make it more than just a passion.

The new NUC is taking all sorts of forms at CES 2020, but none is as slick or as snazzy as Razer's early stab at this power-packed mini-PC platform.

Defying the notion that business-focused smartphones need to be clunky and thick, Samsung's Galaxy XCover Pro is thin, light, and durable. Use it as a walkie-talkie, a mobile point-of-sale (POS) system, and however you get work done.

Andretti Autosport and Chip Ganassi Racing are the first two American teams to commit to a new electric SUV off-road racing series scheduled to begin in 2021

XMB - eXtreme Message Board version 1.9.11.13 suffers from weak crypto and insecure password storage vulnerabilities.

Extreme Networks Aerohive HiveOS versions 11.x and below remote denial of service exploit. An unauthenticated malicious user can trigger a denial of service (DoS) attack when sending specific application layer packets towards the Aerohive NetConfig UI. This proof of concept exploit renders the application unusable for 305 seconds or 5 minutes with a single HTTP request using the action.php5 script calling the CliWindow function thru the _page parameter, denying access to the web server hive user interface.

The NBA says some players can voluntarily return to their team practice facilities starting Friday, with some very specific conditions and only in places where ...

It’s been almost two months since Kenya announced its first Covid-19 case. It’s also been more than a month since President Uhuru Kenyatta first announced cessation of movement for some counties and the nationwide night curfew.