Lorentzian Iterative Hard Thresholding: Robust Compressed Sensing with Prior Information

Commonly employed reconstruction algorithms in compressed sensing (CS) use the $L_2$ norm as the metric for the residual error. However, it is well-known that least squares (LS) based estimators are highly sensitive to outliers present in the measurement vector leading to a poor performance when the noise no longer follows the Gaussian assumption but, instead, is better characterized by heavier-than-Gaussian tailed distributions. In this paper, we propose a robust iterative hard Thresholding (IHT) algorithm for reconstructing sparse signals in the presence of impulsive noise. To address this problem, we use a Lorentzian cost function instead of the $L_2$ cost function employed by the traditional IHT algorithm. We also modify the algorithm to incorporate prior signal information in the recovery process. Specifically, we study the case of CS with partially known support. The proposed algorithm is a fast method with computational load comparable to the LS based IHT, whilst having the advantage of robustness against heavy-tailed impulsive noise. Sufficient conditions for stability are studied and a reconstruction error bound is derived. We also derive sufficient conditions for stable sparse signal recovery with partially known support. Theoretical analysis shows that including prior support information relaxes the conditions for successful reconstruction. Simulation results demonstrate that the Lorentzian-based IHT algorithm significantly outperform commonly employed sparse reconstruction techniques in impulsive environments, while providing comparable performance in less demanding, light-tailed environments. Numerical results also demonstrate that the partially known support inclusion improves the performance of the proposed algorithm, thereby requiring fewer samples to yield an approximate reconstruction.Comment: 28 pages, 9 figures, accepted in IEEE Transactions on Signal Processin

Smile detection in the wild based on transfer learning

Smile detection from unconstrained facial images is a specialized and challenging problem. As one of the most informative expressions, smiles convey basic underlying emotions, such as happiness and satisfaction, which lead to multiple applications, e.g., human behavior analysis and interactive controlling. Compared to the size of databases for face recognition, far less labeled data is available for training smile detection systems. To leverage the large amount of labeled data from face recognition datasets and to alleviate overfitting on smile detection, an efficient transfer learning-based smile detection approach is proposed in this paper. Unlike previous works which use either hand-engineered features or train deep convolutional networks from scratch, a well-trained deep face recognition model is explored and fine-tuned for smile detection in the wild. Three different models are built as a result of fine-tuning the face recognition model with different inputs, including aligned, unaligned and grayscale images generated from the GENKI-4K dataset. Experiments show that the proposed approach achieves improved state-of-the-art performance. Robustness of the model to noise and blur artifacts is also evaluated in this paper

Controlling thermal reactivity with different colors of light

The ability to switch between thermally and photochemically activated reaction channels with an external stimulus constitutes a key frontier within the realm of chemical reaction control. Here, we demonstrate that the reactivity of triazolinediones, powerful coupling agents in biomedical and polymer research, can be effectively modulated by an external photonic field. Specifically, we show that their visible light-induced photopolymerization leads to a quantitative photodeactivation, thereby providing a well-defined off-switch of their thermal reactivity. Based on this photodeactivation, we pioneer a reaction manifold using light as a gate to switch between a UV-induced Diels-Alder reaction with photocaged dienes and a thermal addition reaction with alkenes. Critically, the modulation of the reactivity by light is reversible and the individually addressable reaction pathways can be repeatedly accessed. Our approach thus enables a step change in photochemically controlled reactivity, not only in small molecule ligations, yet importantly in controlled surface and photoresist design

Investigation of chromophoric dissolved organic matter as a freshwater tracer in the Kennebec River Estuary

In an attempt to explore the feasibility of using chromophoric dissolved organic matter (CDOM) as a freshwater tracer in the Kennebec Estuary of Maine, potential causes of the variability of the CDOM absorption coefficient (ag412) in relation to salinity were investigated. A predictable relationship between CDOM variability and factors such as river discharge and season was sought to explain CDOM variability for use in remote sensing. To accomplish these objectives, ag412 was calibrated to continuous underway FDOM measurements using linear regressions from 14 cruises. USGS daily discharge rates were checked for possible relationships with ag412 values. Although no trends were noted, there were elevated CDOM accumulation levels during summer suggestive of summer salt marsh growth. A residence time hypothesis is described to explain the relationship between discharge rates and CDOM accumulation levels in the estuary. The absence of trending in the data suggests that CDOM variability is complex and influenced by multiple factors

Sleep-associated and circadian effects on future-directed memory

Erinnerungen spiegeln vergangene Erfahrungen wieder. Ihre Funktion liegt darin, angemessenes Verhalten in der Gegenwart hervorzubringen und es an zukünftige Situationen anzupassen. Das Gedächtnis für Absichten und Pläne bezieht sich ausdrücklich auf zukünftiges Verhalten und kann demnach zum „auf die Zukunft gerichteten Gedächtnis“ gezählt werden. Zirkadiane (lat. circa, “ungefähr” und diem, “Tag”) Rhythmen geben den Takt für viele Körperfunktionen vor, wovon der Schlaf-Wach-Zyklus wahrscheinlich der offensichtlichste ist. Kognitive Funktionen unterschiedlicher Domänen, darunter die Gedächtnisfunktionen, unterliegen ebenfalls zirkadianen Schwankungen. Ziel dieser Arbeit ist es, die Rolle des Schlafes und der Tageszeit für auf die Zukunft gerichtetes Gedächtnis zu beleuchten. Schlaf wirkt sich förderlich auf die Konsolidierung, das heißt, die Stabilisierung und Reorganisation, von neuen Gedächtnisinhalten, aus. Kürzlich wurde gezeigt, dass Schlaf auch die Konsolidierung von Absichten fördert. Studie 1 dieser Arbeit deckt Voraussetzungen für einen förderlichen Schlafeffekt auf Absichten auf und Studie 2 befasst sich mit der Frage, ob das Gedächtnis für Pläne ebenfalls im Schlaf konsolidiert wird. Kognitive Funktionen wie Gedächtnis und Aufmerksamkeit schwanken im Tagesverlauf parallel zum Niveau der physiologischen Erregung des endogenen zirkadianen Systems. Auf höhere Leistungen am Tag folgt eine Verschlechterung zur Nacht hin, was als Tageszeiteffekt bezeichnet wird. In manchen kognitiven Domänen sind die Leistungen zur bevorzugten Tageszeit besser und zur nicht-bevorzugten Zeit schlechter, was unter dem Synchronie-Effekt bekannt ist. Studie 3 dieser Arbeit befasst sich mit der Frage, ob Absichten einem Tageszeit- oder Synchronie-Effekt unterliegen und ob diese potentiellen Effekte durch Aufmerksamkeit moduliert werden. Die Ergebnisse zeigen, dass Intentionen vom Schlaf profitieren, wenn sie über die Schlafperiode hinweg aktiv sind und wenn sie in zeitlicher Nähe zur anfänglichen Lernsituation instruiert werden. Diese Befunde heben die Zeit nach der Enkodierung als eine kritische Phase hervor, in welcher die dort gemachten Erfahrungen bestimmen, ob Inhalte im nachfolgenden Schlaf konsolidiert werden. Zweitens liefert die vorliegende Arbeit erste Belege, dass das Gedächtnis für Pläne im Schlaf konsolidiert wird. Dieses Ergebnis sollte mit Vorsicht interpretiert werden, da der förderliche Effekt von Schlaf nicht in allen Maßen zu finden ist und keine zirkadiane Kontrolle vorhanden ist. Drittens unterliegen Intentionen einem Tageszeiteffekt. Unabhängig von der zirkadianen Präferenz und dem zur Verfügung stehenden Aufmerksamkeitsniveau werden Intentionen am Abend erfolgreicher ausgeführt als am Morgen. Dies wurde in 3 von 4 Maßen gezeigt. Zusammengenommen konnte ich in diesen Arbeiten zeigen, dass auf die Zukunft gerichtetes Gedächtnis im Schlaf nur unter bestimmten Bedin-gungen konsolidiert wird und dass dieses Gedächtnis einem aufmerksamkeits-unabhängigen Tageszeiteffekt unterliegt, ohne dass die präferierte Tageszeit eine Rolle spielt.Memories reflect past experiences, yet their function is to bear appropriate behavior in the present and adapt it to future situations. The memory for intentions and plans explicitly relates to future behavior and can be counted among ‘future-directed memory’. Circadian (lat. circa, ‘approximately’ and diem, ‘day’) rhythms keep time for many bodily functions, of which the sleep-wake cycle is probably the most obvious. Cognitive functions of different domains among others memory functions likewise underlie circadian variations. The aim of this thesis is to shed light on the role of sleep and time of day in future-directed memories. Sleep has been shown to benefit the consolidation, i.e. the stabilization and reorganization of new memories. Only recently has sleep been proven effective in consolidating intentions. Study 1 of this thesis uncovers conditions for a beneficial sleep effect on intentions and study 2 addresses the question of whether the memory for plans is also consolidated during sleep. Cognitive functions - for example memory and attention - fluctuate throughout the course of a day, in parallel with arousal levels of the endogenous circadian system. Better performance during the day is succeeded by a decline towards the night, which is called the time-of-day effect. For some cognitive domains, performance is higher at preferred times of the day and worse at non-preferred times of the day; this is known as the synchrony effect. Study 3 of this thesis addresses whether intentions underlie a time-of-day effect or a synchrony effect and whether attention modulates these potential effects. Results show that intentions benefit from sleep as long as they are still pending and only if they are instructed in temporal proximity to the initial learning session. These findings highlight the importance of the time after encoding as a sensitive period, in which experiences determine whether memories undergo consolidation during subsequent sleep. Furthermore, the present work delivers tentative evidence that the memory for plans is consolidated during sleep. This result should be interpreted with caution because the beneficial effect of sleep is not present in all measures and because the experiment lacks a circadian control. Thirdly, intentions underlie a time-of-day effect. Independent of circadian preference and the level of available attention, intentions are realized more successfully during evening hours compared to morning hours. This has been shown in 3 out of 4 measures. Together, these results show that future-directed memories are consolidated during sleep only under certain conditions and that they underlie an attention-independent time-of-day effect in the absence of a synchrony effect

The Creation of Primary Sources Digital Collections in an Academic Library

This article discusses the creation of primary sources digital collections in an academic library, including implementation, work processes, digitization and providing accessibility of visual materials. These reflect the practical application of the approach developed in The Younes and Soraya Nazarian Library at the University of Haifa regarding the library\u27s position in the field of digital collections. The article denotes the work process model created for these collections, from their reception, through classification, cataloging, scanning and digitization, and to the digital publishing which provides access. Special emphasis is given to practical ways to manage the challenges that arise from handing unique visual materials such as photos, albums, manuscripts, and maps

Application Software Cybersecurity Scanning

Scanning software applications for cybersecurity vulnerabilities is a crucial step is assessing the overall health of the application, but how can this kind of scan be performed to give development teams the information they need to make informed design decisions? Two pilot cybersecurity scans were conducted in an attempt to answer this question. A scanning team composed of various subject matter experts was established and worked closely with the development team to perform these scans and capture metrics throughout the process. These interactions and metrics indicate that these scans can be performed in an unobtrusive way and still provide valuable information to development teams regarding the health of their application. This work is not definitive in nature but serves as a foundation for future work