Augmented sparse principal component analysis for high dimensional data

We study the problem of estimating the leading eigenvectors of a high-dimensional population covariance matrix based on independent Gaussian observations. We establish lower bounds on the rates of convergence of the estimators of the leading eigenvectors under $l^q$-sparsity constraints when an $l^2$ loss function is used. We also propose an estimator of the leading eigenvectors based on a coordinate selection scheme combined with PCA and show that the proposed estimator achieves the optimal rate of convergence under a sparsity regime. Moreover, we establish that under certain scenarios, the usual PCA achieves the minimax convergence rate.Comment: This manuscript was written in 2007, and a version has been available on the first author's website, but it is posted to arXiv now in its 2007 form. Revisions incorporating later work will be posted separatel

Minimax bounds for sparse PCA with noisy high-dimensional data

We study the problem of estimating the leading eigenvectors of a high-dimensional population covariance matrix based on independent Gaussian observations. We establish a lower bound on the minimax risk of estimators under the $l_2$ loss, in the joint limit as dimension and sample size increase to infinity, under various models of sparsity for the population eigenvectors. The lower bound on the risk points to the existence of different regimes of sparsity of the eigenvectors. We also propose a new method for estimating the eigenvectors by a two-stage coordinate selection scheme.Comment: 1 figur

Adaptation in a class of linear inverse problems

We consider the linear inverse problem of estimating an unknown signal $f$ from noisy measurements on $Kf$ where the linear operator $K$ admits a wavelet-vaguelette decomposition (WVD). We formulate the problem in the Gaussian sequence model and propose estimation based on complexity penalized regression on a level-by-level basis. We adopt squared error loss and show that the estimator achieves exact rate-adaptive optimality as $f$ varies over a wide range of Besov function classes.Comment: 3 figure

Understanding barriers to purchasing healthier, more sustainable food for people living with obesity and food insecurity.

In westernised countries, food insecurity (FI), poorer diet quality, and obesity are disproportionately represented in groups experiencing socio-economic disadvantage. Grocery stores are one promising arena for intervention; however how these settings can facilitate purchasing of healthier, more sustainable food in people living with obesity (PLWO) and FI remains unclear. Using an online survey (N=583), adults residing in England or Scotland with a body mass index of ≥30kg/m2 self-reported on FI, diet quality, and their experiences of shopping in a grocery store for healthy and sustainable food. Using structural equation modelling, greater FI was directly associated with barriers from the food environment (e.g., price), food preparation practices, lower healthy diet knowledge and physical ill-health. Moreover, greater FI was indirectly associated with poorer diet quality via poorer mental health and greater experiences of self-stigma associated with being food insecure. Grocery store interventions based on price or incentivisation were ranked most helpful in supporting healthier, more sustainable purchasing. These findings highlight the challenges faced by this group when shopping and underscore the need for policy development relating to price and affordability at a population-level, and for clinicians to offer tailored, holistic approaches to obesity treatment that acknowledges and minimises stigma and mental health

Direct imaging of correlated defect nanodomains in a metal-organic framework

Defect engineering can enhance key properties of metal-organic frameworks (MOFs). Tailoring the distribution of defects, for example in correlated nanodomains, requires characterization across length scales. However, a critical nanoscale characterization gap has emerged between the bulk diffraction techniques used to detect defect nanodomains and the sub-nanometer imaging used to observe individual defects. Here, we demonstrate that the emerging technique of scanning electron diffraction (SED) can bridge this gap uniquely enabling both nanoscale crystallographic analysis and the lowdose formation of multiple diffraction contrast images for defect analysis in MOFs. We directly image defect nanodomains in the MOF UiO-66(Hf) over an area of ca. 1 000 nm and with a spatial resolution ca. 5 nm to reveal domain morphology and distribution. Based on these observations, we suggest possible crystal growth processes underpinning synthetic control of defect nanodomains. We also identify likely dislocations and small angle grain boundaries, illustrating that SED could be a key technique in developing the potential for engineering the distribution of defects, or “microstructure”, in functional MOF design

Young Stellar Objects in the Gould Belt

We present the full catalog of Young Stellar Objects (YSOs) identified in the 18 molecular clouds surveyed by the Spitzer Space Telescope "cores to disks" (c2d) and "Gould Belt" (GB) Legacy surveys. Using standard techniques developed by the c2d project, we identify 3239 candidate YSOs in the 18 clouds, 2966 of which survive visual inspection and form our final catalog of YSOs in the Gould Belt. We compile extinction corrected SEDs for all 2966 YSOs and calculate and tabulate the infrared spectral index, bolometric luminosity, and bolometric temperature for each object. We find that 326 (11%), 210 (7%), 1248 (42%), and 1182 (40%) are classified as Class 0+I, Flat-spectrum, Class II, and Class III, respectively, and show that the Class III sample suffers from an overall contamination rate by background AGB stars between 25% and 90%. Adopting standard assumptions, we derive durations of 0.40-0.78 Myr for Class 0+I YSOs and 0.26-0.50 Myr for Flat-spectrum YSOs, where the ranges encompass uncertainties in the adopted assumptions. Including information from (sub)millimeter wavelengths, one-third of the Class 0+I sample is classified as Class 0, leading to durations of 0.13-0.26 Myr (Class 0) and 0.27-0.52 Myr (Class I). We revisit infrared color-color diagrams used in the literature to classify YSOs and propose minor revisions to classification boundaries in these diagrams. Finally, we show that the bolometric temperature is a poor discriminator between Class II and Class III YSOs.Comment: Accepted for publication in ApJS. 29 pages, 11 figures, 14 tables, 4 appendices. Full versions of data tables (to be published in machine-readable format by ApJS) available at the end of the latex source cod

The effect of hunger state on hypothalamic functional connectivity in response to food cues

ACKNOWLEDGMENT The authors thank Lisette Charbonnier for her relentless efforts in setting up the study at all three sites and collecting the Dutch data. Open Access funding enabled and organized by Projekt DEAL. FUNDING INFORMATION This work was financially supported by the European Union Seventh Framework Programme (FP7/2007–2013) for research, technological development, and demonstration under grant agreement 266408 (Full4Health, www.full4health.eu). Furthermore, the study was supported in parts by a grant (01GI0925) from the Federal Ministry of Education and Research (BMBF) to the German Center for Diabetes Research (DZD e.V.).Peer reviewedPublisher PD

Learning a Factor Model via Regularized PCA

We consider the problem of learning a linear factor model. We propose a regularized form of principal component analysis (PCA) and demonstrate through experiments with synthetic and real data the superiority of resulting estimates to those produced by pre-existing factor analysis approaches. We also establish theoretical results that explain how our algorithm corrects the biases induced by conventional approaches. An important feature of our algorithm is that its computational requirements are similar to those of PCA, which enjoys wide use in large part due to its efficiency

If the Body Is Part of Our Discourse, Why Not Let It Speak? Five Critical Perspectives

Abstract: Of the five perspectives set forth in this essay, four of them specify obstacles that block experiential understandings of emotions. The obstacles in one way and another subvert the living body, whether presenting it as a mere face or as an ahistorical adult body, as an embodied phenomenon or as a brain unattached to a whole-body nervous system. Such accounts bypass the affective dynamics that move through bodies and move them to move. Being true to the truths of experience, the fifth perspective, requires recognition of our infancy and even of our prenatal lives, both of which are tethered to developmental movement. It furthermore requires recognition of affective realties as subject-world relationships and recognition of the dynamic congruency of emotions and movement. In the end, the perspectives lead us to inquire about “the things themselves.” Keywords: Animate · Dynamic · Brain · Embodied · Infanc

Acquired Resilience: An Evolved System of Tissue Protection in Mammals.

This review brings together observations on the stress-induced regulation of resilience mechanisms in body tissues. It is argued that the stresses that induce tissue resilience in mammals arise from everyday sources: sunlight, food, lack of food, hypoxia and physical stresses. At low levels, these stresses induce an organised protective response in probably all tissues; and, at some higher level, cause tissue destruction. This pattern of response to stress is well known to toxicologists, who have termed it hormesis. The phenotypes of resilience are diverse and reports of stress-induced resilience are to be found in journals of neuroscience, sports medicine, cancer, healthy ageing, dementia, parkinsonism, ophthalmology and more. This diversity makes the proposing of a general concept of induced resilience a significant task, which this review attempts. We suggest that a system of stress-induced tissue resilience has evolved to enhance the survival of animals. By analogy with acquired immunity, we term this system \u27acquired resilience\u27. Evidence is reviewed that acquired resilience, like acquired immunity, fades with age. This fading is, we suggest, a major component of ageing. Understanding of acquired resilience may, we argue, open pathways for the maintenance of good health in the later decades of human life