New York : Experimental Manpower Laboratory at Mobilization for Youth, Inc., [1971]

Emilio Porcu, Rachid Senoussi, Enner Mendoza, Moreno Bevilacqua.

Source: Electronic Journal of Statistics, Volume 14, Number 1, 890--916.

Abstract:
The paper considers reduction problems and deformation approaches for nonstationary covariance functions on the $(d-1)$-dimensional spheres, $mathbb{S}^{d-1}$, embedded in the $d$-dimensional Euclidean space. Given a covariance function $C$ on $mathbb{S}^{d-1}$, we chase a pair $(R,Psi)$, for a function $R:[-1,+1] o mathbb{R}$ and a smooth bijection $Psi$, such that $C$ can be reduced to a geodesically isotropic one: $C(mathbf{x},mathbf{y})=R(langle Psi (mathbf{x}),Psi (mathbf{y}) angle )$, with $langle cdot ,cdot angle $ denoting the dot product. The problem finds motivation in recent statistical literature devoted to the analysis of global phenomena, defined typically over the sphere of $mathbb{R}^{3}$. The application domains considered in the manuscript makes the problem mathematically challenging. We show the uniqueness of the representation in the reduction problem. Then, under some regularity assumptions, we provide an inversion formula to recover the bijection $Psi$, when it exists, for a given $C$. We also give sufficient conditions for reducibility.

Stochastic gradient Langevin dynamics (SGLD) is a fundamental algorithm in stochastic optimization. Recent work by Zhang et al. (2017) presents an analysis for the hitting time of SGLD for the first and second order stationary points. The proof in Zhang et al. (2017) is a two-stage procedure through bounding the Cheeger's constant, which is rather complicated and leads to loose bounds. In this paper, using intuitions from stochastic differential equations, we provide a direct analysis for the hitting times of SGLD to the first and second order stationary points. Our analysis is straightforward. It only relies on basic linear algebra and probability theory tools. Our direct analysis also leads to tighter bounds comparing to Zhang et al. (2017) and shows the explicit dependence of the hitting time on different factors, including dimensionality, smoothness, noise strength, and step size effects. Under suitable conditions, we show that the hitting time of SGLD to first-order stationary points can be dimension-independent. Moreover, we apply our analysis to study several important online estimation problems in machine learning, including linear regression, matrix factorization, and online PCA.

Heat waves resulting from prolonged extreme temperatures pose a significant risk to human health globally. Given the limitations of observations of extreme temperature, climate models are often used to characterize extreme temperature globally, from which one can derive quantities like return values to summarize the magnitude of a low probability event for an arbitrary geographic location. However, while these derived quantities are useful on their own, it is also often important to apply a spatial statistical model to such data in order to, e.g., understand how the spatial dependence properties of the return values vary over space and emulate the climate model for generating additional spatial fields with corresponding statistical properties. For these objectives, when modeling global data it is critical to use a nonstationary covariance function. Furthermore, given that the output of modern global climate models can be on the order of $mathcal{O}(10^4)$, it is important to utilize approximate Gaussian process methods to enable inference. In this paper, we demonstrate the application of methodology introduced in Risser and Turek (2020) to conduct a nonstationary and fully Bayesian analysis of a large data set of 20-year return values derived from an ensemble of global climate model runs with over 50,000 spatial locations. This analysis uses the freely available BayesNSGP software package for R.

Data-driven modelling and computational predictions based on maximum entropy principle (MaxEnt-principle) aim at finding as-simple-as-possible - but not simpler then necessary - models that allow to avoid the data overfitting problem. We derive a multivariate non-parametric and non-stationary formulation of the MaxEnt-principle and show that its solution can be approximated through a numerical maximisation of the sparse constrained optimization problem with regularization. Application of the resulting algorithm to popular financial benchmarks reveals memoryless models allowing for simple and qualitative descriptions of the major stock market indexes data. We compare the obtained MaxEnt-models to the heteroschedastic models from the computational econometrics (GARCH, GARCH-GJR, MS-GARCH, GARCH-PML4) in terms of the model fit, complexity and prediction quality. We compare the resulting model log-likelihoods, the values of the Bayesian Information Criterion, posterior model probabilities, the quality of the data autocorrelation function fits as well as the Value-at-Risk prediction quality. We show that all of the considered seven major financial benchmark time series (DJI, SPX, FTSE, STOXX, SMI, HSI and N225) are better described by conditionally memoryless MaxEnt-models with nonstationary regime-switching than by the common econometric models with finite memory. This analysis also reveals a sparse network of statistically-significant temporal relations for the positive and negative latent variance changes among different markets. The code is provided for open access.

Holger Dette, Weichi Wu.

Source: The Annals of Statistics, Volume 47, Number 6, 3578--3608.

Abstract:
This paper considers the problem of testing if a sequence of means $(mu_{t})_{t=1,ldots ,n}$ of a nonstationary time series $(X_{t})_{t=1,ldots ,n}$ is stable in the sense that the difference of the means $mu_{1}$ and $mu_{t}$ between the initial time $t=1$ and any other time is smaller than a given threshold, that is $|mu_{1}-mu_{t}|leq c$ for all $t=1,ldots ,n$. A test for hypotheses of this type is developed using a bias corrected monotone rearranged local linear estimator and asymptotic normality of the corresponding test statistic is established. As the asymptotic variance depends on the location of the roots of the equation $|mu_{1}-mu_{t}|=c$ a new bootstrap procedure is proposed to obtain critical values and its consistency is established. As a consequence we are able to quantitatively describe relevant deviations of a nonstationary sequence from its initial value. The results are illustrated by means of a simulation study and by analyzing data examples.

Stefan Richter, Rainer Dahlhaus.

Source: The Annals of Statistics, Volume 47, Number 4, 2145--2173.

Abstract:
We propose an adaptive bandwidth selector via cross validation for local M-estimators in locally stationary processes. We prove asymptotic optimality of the procedure under mild conditions on the underlying parameter curves. The results are applicable to a wide range of locally stationary processes such linear and nonlinear processes. A simulation study shows that the method works fairly well also in misspecified situations.

Jessica K. Hargreaves, Marina I. Knight, Jon W. Pitchford, Rachael J. Oakenfull, Sangeeta Chawla, Jack Munns, Seth J. Davis.

Source: The Annals of Applied Statistics, Volume 13, Number 3, 1817--1846.

Abstract:
Rhythmic data are ubiquitous in the life sciences. Biologists need reliable statistical tests to identify whether a particular experimental treatment has caused a significant change in a rhythmic signal. When these signals display nonstationary behaviour, as is common in many biological systems, the established methodologies may be misleading. Therefore, there is a real need for new methodology that enables the formal comparison of nonstationary processes. As circadian behaviour is best understood in the spectral domain, here we develop novel hypothesis testing procedures in the (wavelet) spectral domain, embedding replicate information when available. The data are modelled as realisations of locally stationary wavelet processes, allowing us to define and rigorously estimate their evolutionary wavelet spectra. Motivated by three complementary applications in circadian biology, our new methodology allows the identification of three specific types of spectral difference. We demonstrate the advantages of our methodology over alternative approaches, by means of a comprehensive simulation study and real data applications, using both published and newly generated circadian datasets. In contrast to the current standard methodologies, our method successfully identifies differences within the motivating circadian datasets, and facilitates wider ranging analyses of rhythmic biological data in general.

Ulrike Mayer, Henryk Zähle, Zhou Zhou.

Source: Bernoulli, Volume 26, Number 3, 1891--1911.

Abstract:
We derive a functional weak limit theorem for a local empirical process of a wide class of piece-wise locally stationary (PLS) time series. The latter result is applied to derive the asymptotics of weighted empirical quantiles and weighted V-statistics of non-stationary time series. The class of admissible underlying time series is illustrated by means of PLS linear processes and PLS ARCH processes.

Kamran Kalbasi, Thomas Mountford.

Source: Bernoulli, Volume 26, Number 2, 1504--1534.

Abstract:
In this paper, we study the local times of vector-valued Gaussian fields that are ‘diagonally operator-self-similar’ and whose increments are stationary. Denoting the local time of such a Gaussian field around the spatial origin and over the temporal unit hypercube by $Z$, we show that there exists $lambdain(0,1)$ such that under some quite weak conditions, $lim_{n ightarrow+infty}frac{sqrt[n]{mathbb{E}(Z^{n})}}{n^{lambda}}$ and $lim_{x ightarrow+infty}frac{-logmathbb{P}(Z>x)}{x^{frac{1}{lambda}}}$ both exist and are strictly positive (possibly $+infty$). Moreover, we show that if the underlying Gaussian field is ‘strongly locally nondeterministic’, the above limits will be finite as well. These results are then applied to establish similar statements for the intersection local times of diagonally operator-self-similar Gaussian fields with stationary increments.

Wensheng Wang, Zhonggen Su, Yimin Xiao.

Source: Bernoulli, Volume 26, Number 2, 1410--1430.

Abstract:
We establish the exact moduli of non-differentiability of Gaussian random fields with stationary increments. As an application of the result, we prove that the uniform Hölder condition for the maximum local times of Gaussian random fields with stationary increments obtained in Xiao (1997) is optimal. These results are applicable to fractional Riesz–Bessel processes and stationary Gaussian random fields in the Matérn and Cauchy classes.

The military is preparing to deploy to the region to try to stop illegal logging and mining.

Wood used to build the secret passageway came from a tree felled in 1874, according to a new analysis

<span class="topsy_trackback_comment"><span class="topsy_twitter_username"><span class="topsy_trackback_content">FCC Launches New Round of Audits of Radio Station EEO Performance http://bit.ly/anoP3q</span></span>

Deforestation in Brazil's Amazon rainforest rose sharply in April, government data showed on Friday, as the coronavirus outbreak keeps many environmental enforcers out of the field and the country prepares to deploy troops to fight illegal logging.

Pediatric thrombocytopenia has a wide differential diagnosis, and recently, genetic testing to identify its etiology has become more common. We present a case of a 16-year-old boy with a history of chronic moderate thrombocytopenia, who later developed constitutional symptoms and bilateral hand edema with cold exposure. Laboratory evaluation revealed evidence both of inflammation and elevated muscle enzymes. These abnormalities persisted over months. His thrombocytopenia was determined to be immune mediated. Imaging revealed lymphadenopathy and asplenia, and a muscle biopsy was consistent with tubular aggregate myopathy. Ophthalmology evaluation noted photosensitivity, pupillary miosis, and iris hypoplasia. Genetic testing demonstrated a pathogenic variant in STIM1 consistent with autosomal dominant Stormorken syndrome. Our case is novel because of the overlap of phenotypes ascribed to both gain-of-function and loss-of-function pathogenic variants in STIM1, thereby blurring the distinctions between these previously described syndromes. Pediatricians should consider checking muscle enzymes when patients present with thrombocytopenia and arthralgia, myalgia, and/or muscle weakness. Our case highlights the importance of both multidisciplinary care and genetic testing in cases of chronic unexplained thrombocytopenia. By understanding the underlying genetic mechanism to a patient’s thrombocytopenia, providers are better equipped to make more precise medical management recommendations.

AN EDINBURGH-BASED hydrogen technology firm is to open the first public hydrogen refuelling station for vehicles in Scotland’s central belt.

A man has been found dead outside of a police station in Ayrshire.

Dumbarton police station has temporarily closed after a member of staff showed symptoms of Covid-19.

SOMETIMES, for a giggle, I like to imagine what Scotland would have been like had we kept the oil for ourselves. Like Saudi Arabia without the weather and executions, maybe? Or more like canny Norway, investing the cash in a big brolly for some future rainy day?

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)

Although morbidity-free survival for preterm infants has remained constant in US NICUs when assessed collectively, morbidity-free survival differs among centers. Center-specific practices before, at, or after delivery might affect outcomes of the most premature infants.

Our findings suggest that the approach taken to infants at the limits of viability is associated with outcomes of more-mature infants. Identifying centers with higher survival and lower morbidity might lead to identification of key practices to improve morbidity-free survival. (Read the full article)

Preterm infants from 33 gestational weeks can detect specific shape features (prism and cylinder) by touch (without visual control), and remember them; however, nothing is known about such abilities earlier in development.

The preterm infant, even when very immature (from 28 gestational weeks), is endowed with tactile sensory abilities: the exploration and memorization of an object by touch, the discrimination of a novel object, and the recognition of a familiar object after interference. (Read the full article)

Late preterm infants are at risk for a variety of developmental impairments; however, little is known about developmental differences among children born within the term range of 37 to 41 weeks’ gestation.

This study links comprehensive birth record data from 128 050 term births to children’s school records 8 years later. Analyses establish that, even among the "normal term" range, gestational age is an important independent predictor of academic achievement. (Read the full article)

Birth defects are associated with preterm birth and are a major contributor to infant mortality. There are persistent black-white differences in overall infant mortality and infant mortality attributable to birth defects.

Among infants delivered at 37 to 44 weeks, blacks and Hispanics had significantly higher neonatal and postneonatal mortality attributable to birth defects than whites. Among infants delivered at 20 to 33 or 34 to 36 weeks, neonatal mortality attributable to birth defects was significantly lower among blacks. (Read the full article)

Approximately 80% of all preterm children are born moderately preterm (32–36 weeks’ gestation). Moderately preterm children are at increased risk for developmental delays, but the specific neuropsychological functions that may underlie these delays are unknown.

Moderately preterm birth is associated with poorer performance in intelligence, attention, visuospatial reasoning, and executive functioning. Using gender-specific norms, our data suggest that preterm boys catch up, whereas preterm girls lag behind their peers at 7 years of age. (Read the full article)

Children born small for gestational age (SGA) have increased risk of perinatal morbidity and mortality, neonatal death, and cerebral palsy (CP). Causes of SGA, such as congenital malformations, intrauterine infections, and preeclampsia, are also risk factors for the same outcomes.

In 90% of singletons born SGA, CP is apparently of prenatal origin. Low proportions of intrapartum events leading to CP could not be fully explained by a higher neonatal mortality rate in SGA than in non-SGA children. (Read the full article)

Head circumference (HC) at birth reflects brain development in utero. However, HC charts used in Canada are either dated, mixed-gender, nonrepresentative of lower gestational ages, or reflective of other populations in the world.

We developed recent and gender-specific reference curves for HC at birth for singletons of 23 to 41 completed weeks’ gestational age, which included a large number of very prematurely born infants, reflecting the current geotemporal Canadian population and advances in obstetric care. (Read the full article)

Cognitive and motor developmental test scores of preterm and late preterm infants increase with gestational age. Developmental test scores in full-term infants have not previously been considered to relate to gestational age.

In a cohort of healthy, full-term infants, 37 to 41 weeks, 12-month mental and psychomotor scores on the Bayley Scales of Infant Development increased with gestational age, suggesting that neurodevelopment is optimal in infants born at 39 to 41 weeks. (Read the full article)

The remarkable improvement in the survival of extremely premature infants has been well documented. However, there have been few cohort studies large enough to determine the neurodevelopmental outcomes of survivors born at 22 or 23 weeks.

The proportions of unimpaired or minimally impaired were 12.0% at 22 weeks (n = 75) and 20.0% at 23 weeks (n = 245). The outcomes were inferior compared with those for infants born at 24 and 25 weeks, but were improved compared with those in previous studies. (Read the full article)

Preterm birth is associated with increased morbidity during childhood. Many studies have focused on outcomes for preterm births before 32 weeks’ gestation, but there are few follow-up data for late preterm infants (34–36 weeks’ gestation).

The risk of respiratory admission during childhood decreased with each successive week in gestation up to 40 to 42 weeks. The increased risk is small for late preterm infants, but the number affected is large and has an impact on health care services. (Read the full article)

The management of term and near-term newborns suspected of early-onset sepsis, particularly when they are not clearly symptomatic, remains controversial. Methods for quantifying risk that combine maternal factors with a newborn's evolving clinical examination have been lacking.

This study provides a method for predicting risk of early-onset sepsis. It combines maternal risk factors with objective measures of a newborn's clinical examination and places newborns into 3 risk groups (treat empirically, observe and evaluate, and continued observation). (Read the full article)

Preterm (PT) birth is negatively associated with growth. Particularly small for gestational age PT infants are at risk for delays in growth, whereas knowledge about the consequences regarding growth of large for gestational age PT birth is lacking.

During infancy, growth in height, weight, and head circumference of large for gestational age PT infants was well balanced and sufficient. Subsequently, however, weight gain accelerated and resulted in high BMIs compared with the World Health Organization Multicentre Growth Reference Study population. (Read the full article)

Population-based references of birth weight for gestational age are useful indices of birth size in clinical and research settings.

This article uses 2009–2010 US natality data and corrects for likely errors in gestational age dating to yield an up-to-date birth weight for gestational age reference. (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)

Preterm birth has been associated with increased risk of venous thromboembolism (VTE) in infancy, but the longer-term risk is unknown.

In a large national cohort, low gestational age at birth was associated with increased risk of VTE in infancy, early childhood, and young adulthood. These findings call for better awareness of the long-term risk of VTE among preterm birth survivors. (Read the full article)

There is growing evidence reporting that moderately preterm, late preterm, and early term infants are at increased risk of developmental delay. The characteristics of this association are not well established in the literature.

In a sample of infants born between 32 and 41 weeks, there was an inverse and "dose response" relationship between gestational age and developmental delay risk using the ASQ at 8 and 18 months of corrected postnatal age. (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)

Small-for-gestational-age neonates are at risk for thrombocytopenia during the first days and weeks after birth. However, the incidence, duration, severity, responsible mechanism, value of platelet transfusions, and risk of death from this variety of neonatal thrombocytopenia are unknown.

Ten percent of thrombocytopenic small-for-gestational-age neonates have a recognized cause for low platelets (aneuploidy, extracorporeal membrane oxygenation, disseminated intravascular coagulation); they have a high mortality rate (65%). Ninety percent have a moderate, transient (2 weeks), hyporegenerative thrombocytopenia with a low mortality rate (2%). (Read the full article)

Small for gestational age neonates (weight <10th percentile) are at risk for neutropenia during the first days after birth. However, the duration, responsible mechanism, and outcomes of this variety of neonatal neutropenia are not precisely known.

Six percent of small for gestational age neonates had neutrophils <1000/μL, with an average neutropenia duration of 7 days. Neutropenia was more closely linked with small for gestational age status than maternal hypertension. This neutropenia is associated with elevated nucleated red blood cell count and increased odds of necrotizing enterocolitis. (Read the full article)

Maternal gestational weight gain is associated with childhood overweight. It is unknown whether gestational weight gain programs the child’s health or whether gestational weight gain is an indicator of postnatal behavioral factors.

We disentangled these influences by studying the effect of gestational weight gain simultaneously with postdelivery maternal weight change as an indicator for shared family lifestyle on child’s weight development and found that both had an independent effect. (Read the full article)

Sony has been granted a patent for a new PlayStation controller that features two more buttons than the existing DualShock 4 model, but don't look for it with the PS5.

Gaming desktops have all the glamour, but even they must bow to the most serious PCs on the planet: workstations certified to crunch through the most demanding design and rendering jobs and make sense of the hugest datasets. Here's what you need to know as you shop for a genuine heavyweight (even if it's small in size).

The Synology DiskStation DS419slim is a small but powerful four-bay network-attached storage device that offers many of the same features found on bigger, more expensive models.

Need serious mobile muscle for design, creative, or scientific work? These über-laptops with serious specs take the toughest professional applications on the road.

The latest Astro Gaming A50 wireless gaming headset feels and sounds excellent, but it's a pricey option in an increasingly competitive field.

The internal Windows 10 builds that leaked last week ended up revealing a brand new edition of the OS Microsoft is planning for power users.

Ever thought you could help save the rainforest without ever visiting the rainforest? Probably not, but now is your chance, and you can use it as your way to give back this Earth Day. This year, Earth Day celebrations will look different for everyone as we work to find meaningful [...]

Celebrate Earth Day virtually with your teen: Deforestation meets AI was published on SAS Voices by Lucy Kosturko

Turkey hunt day for youth and non-ambulatory disabled hunters April 4, regular turkey season opens April 11.