Johan A.K. Suykens, Carlos Alzate, Kristiaan Pelckmans

Source: Statist. Surv., Volume 4, 148--183.

Abstract:
This paper discusses the role of primal and (Lagrange) dual model representations in problems of supervised and unsupervised learning. The specification of the estimation problem is conceived at the primal level as a constrained optimization problem. The constraints relate to the model which is expressed in terms of the feature map. From the conditions for optimality one jointly finds the optimal model representation and the model estimate. At the dual level the model is expressed in terms of a positive definite kernel function, which is characteristic for a support vector machine methodology. It is discussed how least squares support vector machines are playing a central role as core models across problems of regression, classification, principal component analysis, spectral clustering, canonical correlation analysis, dimensionality reduction and data visualization.

In this paper we introduce plan2vec, an unsupervised representation learning approach that is inspired by reinforcement learning. Plan2vec constructs a weighted graph on an image dataset using near-neighbor distances, and then extrapolates this local metric to a global embedding by distilling path-integral over planned path. When applied to control, plan2vec offers a way to learn goal-conditioned value estimates that are accurate over long horizons that is both compute and sample efficient. We demonstrate the effectiveness of plan2vec on one simulated and two challenging real-world image datasets. Experimental results show that plan2vec successfully amortizes the planning cost, enabling reactive planning that is linear in memory and computation complexity rather than exhaustive over the entire state space.

Emanuele Dolera, Stefano Favaro.

Source: Bernoulli, Volume 26, Number 2, 1294--1322.

Abstract:
Given a sequence ${X_{n}}_{ngeq 1}$ of exchangeable Bernoulli random variables, the celebrated de Finetti representation theorem states that $frac{1}{n}sum_{i=1}^{n}X_{i}stackrel{a.s.}{longrightarrow }Y$ for a suitable random variable $Y:Omega ightarrow [0,1]$ satisfying $mathsf{P}[X_{1}=x_{1},dots ,X_{n}=x_{n}|Y]=Y^{sum_{i=1}^{n}x_{i}}(1-Y)^{n-sum_{i=1}^{n}x_{i}}$. In this paper, we study the rate of convergence in law of $frac{1}{n}sum_{i=1}^{n}X_{i}$ to $Y$ under the Kolmogorov distance. After showing that a rate of the type of $1/n^{alpha }$ can be obtained for any index $alpha in (0,1]$, we find a sufficient condition on the distribution of $Y$ for the achievement of the optimal rate of convergence, that is $1/n$. Besides extending and strengthening recent results under the weaker Wasserstein distance, our main result weakens the regularity hypotheses on $Y$ in the context of the Hausdorff moment problem.

Mathieu Wolff
Jan 2, 2019; 39:3-14
Viewpoints

Fatma Deniz
Sep 25, 2019; 39:7722-7736
BehavioralSystemsCognitive

R Shadmehr
May 1, 1994; 14:3208-3224
Articles

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People have been giving presentations for thousands of years, from Moses with his stone tablets to Elon Musk revealing his grand plans to colonize Mars. While the elements of a great pitchman generally have remained the same over the past 5,000 years -- conviction, charisma, credibility -- today's successful presenters do more than just get in front of an audience and talk.

Knowledge about objects encompasses not only their prototypical features but also complex, atypical, semantic knowledge (e.g., "Pizza was invented in Naples"). This fMRI study of male and female human participants combines univariate and multivariate analyses to consider the cortical representation of this more complex semantic knowledge. Using the categories of food, people, and places, this study investigates whether access to spatially related geographic semantic knowledge (1) involves the same domain-selective neural representations involved in access to prototypical taste knowledge about food; and (2) elicits activation of neural representations classically linked to places when this geographic knowledge is accessed about food and people. In three experiments using word stimuli, domain-relevant and atypical conceptual access for the categories food, people, and places were assessed. Results uncover two principles of semantic representation: food-selective representations in the left insula continue to be recruited when prototypical taste knowledge is task-irrelevant and under conditions of high cognitive demand; access to geographic knowledge for food and people categories involves the additional recruitment of classically place-selective parahippocampal gyrus, retrosplenial complex, and transverse occipital sulcus. These findings underscore the importance of object category in the representation of a broad range of knowledge, while showing how the cross recruitment of specialized representations may endow the considerable flexibility of our complex semantic knowledge.

SIGNIFICANCE STATEMENT We know not only stereotypical things about objects (an apple is round, graspable, edible) but can also flexibly combine typical and atypical features to form complex concepts (the metaphorical role an apple plays in Judeo-Christian belief). In this fMRI study, we observe that, when atypical geographic knowledge is accessed about food dishes, domain-selective sensorimotor-related cortical representations continue to be recruited, but that regions classically associated with place perception are additionally engaged. This interplay between categorically driven representations, linked to the object being accessed, and the flexible recruitment of semantic stores linked to the content being accessed, provides a potential mechanism for the broad representational repertoire of our semantic system.

Human ventral temporal cortex (VTC) is critical for visual recognition. It is thought that this ability is supported by large-scale patterns of activity across VTC that contain information about visual categories. However, it is unknown how category representations in VTC are organized at the submillimeter scale and across cortical depths. To fill this gap in knowledge, we measured BOLD responses in medial and lateral VTC to images spanning 10 categories from five domains (written characters, bodies, faces, places, and objects) at an ultra-high spatial resolution of 0.8 mm using 7 Tesla fMRI in both male and female participants. Representations in lateral VTC were organized most strongly at the general level of domains (e.g., places), whereas medial VTC was also organized at the level of specific categories (e.g., corridors and houses within the domain of places). In both lateral and medial VTC, domain-level and category-level structure decreased with cortical depth, and downsampling our data to standard resolution (2.4 mm) did not reverse differences in representations between lateral and medial VTC. The functional diversity of representations across VTC partitions may allow downstream regions to read out information in a flexible manner according to task demands. These results bridge an important gap between electrophysiological recordings in single neurons at the micron scale in nonhuman primates and standard-resolution fMRI in humans by elucidating distributed responses at the submillimeter scale with ultra-high-resolution fMRI in humans.

SIGNIFICANCE STATEMENT Visual recognition is a fundamental ability supported by human ventral temporal cortex (VTC). However, the nature of fine-scale, submillimeter distributed representations in VTC is unknown. Using ultra-high-resolution fMRI of human VTC, we found differential distributed visual representations across lateral and medial VTC. Domain representations (e.g., faces, bodies, places, characters) were most salient in lateral VTC, whereas category representations (e.g., corridors/houses within the domain of places) were equally salient in medial VTC. These results bridge an important gap between electrophysiological recordings in single neurons at a micron scale and fMRI measurements at a millimeter scale.

It has been proposed that people can generate probabilistic predictions at multiple levels of representation during language comprehension. We used magnetoencephalography (MEG) and electroencephalography (EEG), in combination with representational similarity analysis, to seek neural evidence for the prediction of animacy features. In two studies, MEG and EEG activity was measured as human participants (both sexes) read three-sentence scenarios. Verbs in the final sentences constrained for either animate or inanimate semantic features of upcoming nouns, and the broader discourse context constrained for either a specific noun or for multiple nouns belonging to the same animacy category. We quantified the similarity between spatial patterns of brain activity following the verbs until just before the presentation of the nouns. The MEG and EEG datasets revealed converging evidence that the similarity between spatial patterns of neural activity following animate-constraining verbs was greater than following inanimate-constraining verbs. This effect could not be explained by lexical-semantic processing of the verbs themselves. We therefore suggest that it reflected the inherent difference in the semantic similarity structure of the predicted animate and inanimate nouns. Moreover, the effect was present regardless of whether a specific word could be predicted, providing strong evidence for the prediction of coarse-grained semantic features that goes beyond the prediction of individual words.

SIGNIFICANCE STATEMENT Language inputs unfold very quickly during real-time communication. By predicting ahead, we can give our brains a "head start," so that language comprehension is faster and more efficient. Although most contexts do not constrain strongly for a specific word, they do allow us to predict some upcoming information. For example, following the context of "they cautioned the...," we can predict that the next word will be animate rather than inanimate (we can caution a person, but not an object). Here, we used EEG and MEG techniques to show that the brain is able to use these contextual constraints to predict the animacy of upcoming words during sentence comprehension, and that these predictions are associated with specific spatial patterns of neural activity.

A new study ties the ousting of women directors, actors, producers and screenwriters to the rise of entertainment studios

Closing arguments were presented at the trial of Phillip Lionel Levac on Friday at Regina Court of Queen's Bench.

With a discovery that could rewrite the immunology textbooks, an international group of scientists, including the teams of Bart Lambrecht, Martin Guilliams, Hamida Hammad, and Charlotte Scott (all from the VIB-UGent Center for Inflammation Research) identified a new type of antigen-presenting immune cell.

Overcoming scorching heat and little rain, experimental vineyards teach winemakers to cope with climate change

Kiuna College hopes to play an active role in the emergence of the next generation of Indigenous filmmakers and creators.

Avid curler Dale Kohlenberg, 64, got a lucky break when he was seconded to Iqaluit — and was quickly scouted for Team Nunavut.

Introductory remarks (by videoconference) by Mr Luis de Guindos, Vice-President of the European Central Bank, to the Committee on Economic and Monetary Affairs of the European Parliament, Frankfurt am Main, 7 May 2020.

KIRSTY WILSON, BEECHGROVE PRESENTER

The U.S. Supreme Court declined to take up a case that held the potential to deal a further blow to public-employee unions after last year's "Janus" decision.

Necrotizing enterocolitis (NEC) can present within the first week of life in term infants. In preterm infants, NEC usually appears after commencement of feeds and can occur between 2 and 3 weeks of life.

Among infants <33 weeks’ gestation, NEC appears to occur at mean age of 7 days in more mature infants, whereas onset of NEC is delayed to 32 days of age in smaller, lower gestational age 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)

Late-onset hypocalcemia is common in neonates, often presents with seizures or tetany, and is often attributed to transient hypoparathyroidism.

Late-onset hypocalcemia in neonates is often a sign of coexisting vitamin D deficiency and hypomagnesemia and is readily managed with therapy of limited duration, and neonates presenting with tetany or seizures due to hypocalcemia are unlikely to benefit from neuroimaging studies. (Read the full article)

The rapidly rising prevalence of overweight and obesity among children and adolescents over the past 4 decades is a significant public health concern. Experts urge pediatric health care providers to provide routine obesity screening and counseling.

We provide the first nationally representative estimates of the rate of screening and counseling for adolescent obesity by pediatric health professionals. We also examine how socioeconomic factors and access to health care affect whether adolescents receive these services. (Read the full article)

Physical punishment is associated with aggression, delinquency, and internalizing conditions in childhood, as well as a range of Axis I mental disorders in adulthood. More research is needed on the possible long-term relationship between physical punishment and mental health.

To our knowledge, this is the first nationally representative examination of physical punishment and a range of Axis I and II disorders, gender interactions, and proportion of mental disorders in the general population that may be attributable to physical punishment. (Read the full article)

Increased computed tomography (CT) use among adults and children presenting to emergency departments has spawned concern about associated radiation exposure. The risks and benefits of CT use for certain conditions, such as abdominal pain, among general pediatric populations remains unclear.

This study analyzes emergency department radiology trends between 1998 and 2008 among children with abdominal pain, highlighting a dramatic increase in CT use. Factors associated with CT ordering include older age, non-black race, and hospital admission. (Read the full article)

Tobacco smoke exposure is associated with increased morbidity in children, and exposure in cars can be particularly intense. The American Academy of Pediatrics policy statement recommends that pediatricians assist families in adopting smoke-free car policies.

In this study, few smoking parents had a strictly enforced smoke-free car policy. Low rates of pediatric health care providers addressing smoking in the car highlights the need for improved pediatric interventions to protect children from tobacco smoke toxins. (Read the full article)

Violence involving firearms is a leading cause of death among US youth ages 14 to 24. The emergency department is the primary medical setting for care of assault-injured youth and an underused but important setting for violence-prevention programs.

Among assault-injured youth seeking emergency department care, firearm possession rates are high, most obtained outside of legal channels. Higher rates of negative retaliatory attitudes and substance use among those youth with firearms increases risk of future lethal violence. (Read the full article)

Delivering competent oral case presentations is an important clinical communication skill, yet effective means of improving trainees’ presentations have not been identified.

Oral presentation feedback sessions facilitated by faculty by using an 18-item competency-based evaluation form early in pediatric clerkships improved medical students’ subsequent oral presentations. Medical schools should consider implementing this evidence-supported practice. (Read the full article)

Early detection of scoliosis facilitates treatment. For detection, topographic features, such as truncal asymmetry or rib hump, are used.

We show a correlation between curve magnitude at presentation and BMI. Obesity may obscure physical examination findings. (Read the full article)

Associations have been reported between celiac disease (CD) and numerous autoimmune conditions in adults and children. However, current screening guidelines do not consider patients with rheumatic diseases to be at high risk for CD.

The prevalence of CD in children presenting for rheumatology evaluation was found to be 2% by routine serologic screening. The majority of screening-detected CD cases had no CD-associated symptoms. Gluten restriction was found to relieve some musculoskeletal complaints. (Read the full article)

Tricycle riding is a common activity in children. In calendar year 2012, tricycle accidents were the most common cause of reported toy-related deaths in children. Little research has been conducted regarding tricycle-related injuries and how to counsel parents appropriately.

This study uses nationally representative data to investigate various characteristics of tricycle-related injuries in children to better counsel parents. This study highlights the importance of helmet and elbow pad use and parental supervision. (Read the full article)

The HUB-Robeson Galleries are proud to present "moments," an online thesis exhibition of photography by Zsuzsanna Nagy, a second-year master of fine arts student in photography.

Having student board members with voting clout on school boards poses a number of logistical challenges, readers say in response to a recent Education Week feature.

Terrie E. Inder
Feb 1, 2005; 115:286-294
ARTICLES

England won the 2017 Maurice Burlaz Trophy, the prize awarded to the nation that achieved the best results in UEFA's men's youth competitions over the previous two seasons.

Penn State Abington students involved in undergraduate research quickly designed ways to present their findings online. It mirrors a global effort as many academic conferences transitioned to online due to the coronavirus pandemic.

Penn State Wilkes-Barre held its 31st annual Celebration of Academic Excellence event on April 30. Due to the COVID-19 pandemic, this year’s ceremony was held in a virtual format.

Autumn Sabo, assistant professor of biology, and Yi-An Burleson, assistant professor of psychology, will present on their respective areas of research for the Academic Affairs Faculty Speaker Series.

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When asked to share his testimony, a participant of OM Chile's Adventure Team realises just how much God has worked in his life.

Play features Dr. Who, the time traveler, who brings William Penn back to Dover.

THE DELAWARE DIVISION OF THE ARTS TO HOST A FREE ACCESSIBILITY PRESENTATION LED BY THE NATIONAL ENDOWMENT FOR THE ARTS Dr. Beth Bienvenu, accessibility director, will review how to make the arts accessible to all Wilmington, Del. (November 30, 2017) – Building off of this year’s Arts Summit theme: “Arts for All” and an earlier […]