Home Drying of Foods

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Fixation sequences in imagery and in recognition during the processing of pictures of real-world scenes

Thirty photographs of real-world scenes were presented for encoding, and half the participants then performed a recognition test, deciding whether each of 60 images were old (from the original set) or new. The other participants performed an imagery task immediately after encoding each of the 30 images. After completing this task, the recognition group then performed the imagery task in response to prompts that were unique verbal descriptors, and the imagery group performed the recognition task. All participants returned 2 days later, and repeated the imagery test. Eye movements were recorded during all phases. Differences in average fixation duration, average number of fixations and average saccadic amplitude were found between task groups and between experimental phases. Scan patterns were compared with a string-editing algorithm. Close similarities were observed between experimental phases that involved more similar tasks (e.g., initial encoding vs. recognition, and immediate imagery vs. delayed imagery). Scan patterns were equally similar when the task was presented immediately or after 2 days. We propose that the more similar the encoding and retrieval processes are, the more similar eye movements will be at each of these experimental stages

Eye movements and scanpaths in the perception of real-world scenes

The way we move our eyes when viewing a scene is not random, but is influenced by both bottom-up (low-level), and top-down (cognitive) factors. This Thesis investigates not only what these influences are and how they effect eye movements, but more importantly how they interact with each other to guide visual perception of real-world scenes. Experiments 1 and 2 show that the sequences of fixations and saccades - ‘scanpaths’ - generated when encoding a picture are replicated both during imagery and at recognition. Higher scanpath similarities at recognition suggest that low-level visual information plays an important role in guiding eye movements, yet the above-chance similarities at imagery argue against a purely bottom-up explanation and imply a link between eye movements and visual memory. This conclusion is supported by increased scanpath similarities when previously seen pictures are described from memory (experiment 3). When visual information is available, areas of high visual saliency attract attention and are fixated sooner than less salient regions. This effect, however, is reliably reduced when viewers possess top-down knowledge about the scene in the form of domain proficiency (experiments 4-6). Enhanced memory, as well as higher scanpath similarity, for domain-specific pictures exists at recognition, and in the absence of visual information when previously seen pictures are described from memory, but not when simply imagined (experiment 6). As well as the cognitive override of bottom-up saliency, domain knowledge also moderates the influence of top-down incongruence during scene perception (experiment 7). Object-intrinsic oddities are less likely to be fixated when participants view pictures containing other domain-relevant semantic information. The finding that viewers fixate the most informative parts of a scene was extended to investigate the presence of social (people) and emotional information, both of which were found to enhance recognition memory (experiments 8 and 9). However, the lack of relationship between string similarity and accuracy, when viewing ‘people’ pictures, challenges the idea that the reproduction of eye movements alone is enough to create this memory advantage (experiment 8). It is therefore likely that the semantically informative parts of a scene play a large role in guiding eye movements and enhancing memory for a scene. The processing of emotional features occurs at a very early stage of perception (even when they are still in the parafoveal), but once fixated only emotionally negative (not positive) features hold attention (experiment 9). The presence of these emotionally negative features also reliably decreases the influence of saliency on eye movements. Lastly, experiment 10 illustrates that although the fixation sequence is important for recognition memory, the influence of visually salient and semantically relevant parafoveal cues in real-world scenes decreases the necessity to fixate in the same order. These experiments combine to conclude that eye movements are neither influenced by purely top-down nor bottom-up factors, but instead a combination of both, which interact to guide attention to the most relevant parts of the picture

The Dopaminergic System in the Aging Brain of Drosophila

Drosophila models of Parkinson's disease are characterized by two principal phenotypes: the specific loss of dopaminergic (DA) neurons in the aging brain and defects in motor behavior. However, an age-related analysis of these baseline parameters in wildtype Drosophila is lacking. Here we analyzed the DA system and motor behavior in aging Drosophila. DA neurons in the adult brain can be grouped into bilateral symmetric clusters, each comprising a stereotypical number of cells. Analysis of TH > mCD8::GFP and cell type-specific MARCM clones revealed that DA neurons show cluster-specific, stereotypical projection patterns with terminal arborization in target regions that represent distinct functional areas of the adult brain. Target areas include the mushroom bodies, involved in memory formation and motivation, and the central complex, involved in the control of motor behavior, indicating that similar to the mammalian brain, DA neurons in the fly brain are involved in the regulation of specific behaviors. Behavioral analysis revealed that Drosophila show an age-related decline in startle-induced locomotion and negative geotaxis. Motion tracking however, revealed that walking activity, and exploration behavior, but not centrophobism increase at late stages of life. Analysis of TH > Dcr2, mCD8::GFP revealed a specific effect of Dcr2 expression on walking activity but not on exploratory or centrophobic behavior, indicating that the siRNA pathway may modulate distinct DA behaviors in Drosophila. Moreover, DA neurons were maintained between early- and late life, as quantified by TH > mCD8::GFP and anti-TH labeling, indicating that adult onset, age-related degeneration of DA neurons does not occur in the aging brain of Drosophila. Taken together, our data establish baseline parameters in Drosophila for the study of Parkinson's disease as well as other disorders affecting DA neurons and movement control

Eye movements and scanpaths in the perception of real-world scenes

The way we move our eyes when viewing a scene is not random, but is influenced by both bottom-up (low-level), and top-down (cognitive) factors. This Thesis investigates not only what these influences are and how they effect eye movements, but more importantly how they interact with each other to guide visual perception of real-world scenes. Experiments 1 and 2 show that the sequences of fixations and saccades - ‘scanpaths’ - generated when encoding a picture are replicated both during imagery and at recognition. Higher scanpath similarities at recognition suggest that low-level visual information plays an important role in guiding eye movements, yet the above-chance similarities at imagery argue against a purely bottom-up explanation and imply a link between eye movements and visual memory. This conclusion is supported by increased scanpath similarities when previously seen pictures are described from memory (experiment 3). When visual information is available, areas of high visual saliency attract attention and are fixated sooner than less salient regions. This effect, however, is reliably reduced when viewers possess top-down knowledge about the scene in the form of domain proficiency (experiments 4-6). Enhanced memory, as well as higher scanpath similarity, for domain-specific pictures exists at recognition, and in the absence of visual information when previously seen pictures are described from memory, but not when simply imagined (experiment 6). As well as the cognitive override of bottom-up saliency, domain knowledge also moderates the influence of top-down incongruence during scene perception (experiment 7). Object-intrinsic oddities are less likely to be fixated when participants view pictures containing other domain-relevant semantic information. The finding that viewers fixate the most informative parts of a scene was extended to investigate the presence of social (people) and emotional information, both of which were found to enhance recognition memory (experiments 8 and 9). However, the lack of relationship between string similarity and accuracy, when viewing ‘people’ pictures, challenges the idea that the reproduction of eye movements alone is enough to create this memory advantage (experiment 8). It is therefore likely that the semantically informative parts of a scene play a large role in guiding eye movements and enhancing memory for a scene. The processing of emotional features occurs at a very early stage of perception (even when they are still in the parafoveal), but once fixated only emotionally negative (not positive) features hold attention (experiment 9). The presence of these emotionally negative features also reliably decreases the influence of saliency on eye movements. Lastly, experiment 10 illustrates that although the fixation sequence is important for recognition memory, the influence of visually salient and semantically relevant parafoveal cues in real-world scenes decreases the necessity to fixate in the same order. These experiments combine to conclude that eye movements are neither influenced by purely top-down nor bottom-up factors, but instead a combination of both, which interact to guide attention to the most relevant parts of the picture

Preservation Methods Differ in Fecal Microbiome Stability, Affecting Suitability for Field Studies.

Immediate freezing at -20°C or below has been considered the gold standard for microbiome preservation, yet this approach is not feasible for many field studies, ranging from anthropology to wildlife conservation. Here we tested five methods for preserving human and dog fecal specimens for periods of up to 8 weeks, including such types of variation as freeze-thaw cycles and the high temperature fluctuations often encountered under field conditions. We found that three of the methods-95% ethanol, FTA cards, and the OMNIgene Gut kit-can preserve samples sufficiently well at ambient temperatures such that differences at 8 weeks are comparable to differences among technical replicates. However, even the worst methods, including those with no fixative, were able to reveal microbiome differences between species at 8 weeks and between individuals after a week, allowing meta-analyses of samples collected using various methods when the effect of interest is expected to be larger than interindividual variation (although use of a single method within a study is strongly recommended to reduce batch effects). Encouragingly for FTA cards, the differences caused by this method are systematic and can be detrended. As in other studies, we strongly caution against the use of 70% ethanol. The results, spanning 15 individuals and over 1,200 samples, provide our most comprehensive view to date of storage effects on stool and provide a paradigm for the future studies of other sample types that will be required to provide a global view of microbial diversity and its interaction among humans, animals, and the environment. IMPORTANCE Our study, spanning 15 individuals and over 1,200 samples, provides our most comprehensive view to date of storage and stabilization effects on stool. We tested five methods for preserving human and dog fecal specimens for periods of up to 8 weeks, including the types of variation often encountered under field conditions, such as freeze-thaw cycles and high temperature fluctuations. We show that several cost-effective methods provide excellent microbiome stability out to 8 weeks, opening up a range of field studies with humans and wildlife that would otherwise be cost-prohibitive

Bis(Imino)Acenaphthene (BIAN)-Supported Palladium(II) Carbene Complexes as Effective C-C Coupling Catalysts and Solvent Effects in Organic and Aqueous Media

The synthesis and catalytic properties of two new 1,2-acenaphthenyl N-heterocyclic carbene-supported palladium(II) catalysts are presented. The acenaphthenyl carbene has been prepared with mesityl or 1,5-diisopropyl N-aryl substituents. Comprehensive catalytic studies for the Suzuki coupling of aryl halides with aryl boronic acids have been conducted. In general, the diisopropyl-functionalised catalyst showed superior selectivity and reactivity. A comparison of the catalytic performances in dichloromethane, toluene and water at low temperatures (30- 40 degrees C) is also presented. Both catalysts were proficient in the homogeneous Suzuki coupling of aryl iodides, bromides and chlorides with boronic acids in dichloromethane. Similar reactions in water led to the formation of insoluble colloidal catalytic species that still exhibited high activity in the Suzuki reaction with aryl chlorides. Reactions performed in toluene showed intermediate results; partial catalyst decomposition led to concomitant homogeneous and heterogeneous catalysis. The heterogeneous palladium precipitates could be easily recovered by filtration and reactivated for subsequent use. Activation energies determined for aryl bromide-based Suzuki reactions were found to be in the range of 159-171 kJ mol(-1) in organic solvents and 111-116 kJ mol(-1) in water. The corresponding activation energy for the aryl chloride was found to be 322 kJ mol(-1) in water.Robert A. Welch Foundation F-1738, F-003Chemistr

Brain DNA methylomic analysis of frontotemporal lobar degeneration reveals OTUD4 in shared dysregulated signatures across pathological subtypes

Frontotemporal lobar degeneration (FTLD) is an umbrella term describing the neuropathology of a clinically, genetically and pathologically heterogeneous group of diseases, including frontotemporal dementia (FTD) and progressive supranuclear palsy (PSP). Among the major FTLD pathological subgroups, FTLD with TDP-43 positive inclusions (FTLD-TDP) and FTLD with tau-positive inclusions (FTLD-tau) are the most common, representing about 90% of the cases. Although alterations in DNA methylation have been consistently associated with neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease, little is known for FTLD and its heterogeneous subgroups and subtypes. The main goal of this study was to investigate DNA methylation variation in FTLD-TDP and FTLD-tau. We used frontal cortex genome-wide DNA methylation profiles from three FTLD cohorts (142 FTLD cases and 92 controls), generated using the Illumina 450K or EPIC microarrays. We performed epigenome-wide association studies (EWAS) for each cohort followed by meta-analysis to identify shared differentially methylated loci across FTLD subgroups/subtypes. In addition, we used weighted gene correlation network analysis to identify co-methylation signatures associated with FTLD and other disease-related traits. Wherever possible, we also incorporated relevant gene/protein expression data. After accounting for a conservative Bonferroni multiple testing correction, the EWAS meta-analysis revealed two differentially methylated loci in FTLD, one annotated to OTUD4 (5'UTR-shore) and the other to NFATC1 (gene body-island). Of these loci, OTUD4 showed consistent upregulation of mRNA and protein expression in FTLD. In addition, in the three independent co-methylation networks, OTUD4-containing modules were enriched for EWAS meta-analysis top loci and were strongly associated with the FTLD status. These co-methylation modules were enriched for genes implicated in the ubiquitin system, RNA/stress granule formation and glutamatergic synaptic signalling. Altogether, our findings identified novel FTLD-associated loci, and support a role for DNA methylation as a mechanism involved in the dysregulation of biological processes relevant to FTLD, highlighting novel potential avenues for therapeutic development

A Transcriptomic Signature of the Hypothalamic Response to Fasting and BDNF Deficiency in Prader-Willi Syndrome.

Transcriptional analysis of brain tissue from people with molecularly defined causes of obesity may highlight disease mechanisms and therapeutic targets. We performed RNA sequencing of hypothalamus from individuals with Prader-Willi syndrome (PWS), a genetic obesity syndrome characterized by severe hyperphagia. We found that upregulated genes overlap with the transcriptome of mouse Agrp neurons that signal hunger, while downregulated genes overlap with the expression profile of Pomc neurons activated by feeding. Downregulated genes are expressed mainly in neuronal cells and contribute to neurogenesis, neurotransmitter release, and synaptic plasticity, while upregulated, predominantly microglial genes are involved in inflammatory responses. This transcriptional signature may be mediated by reduced brain-derived neurotrophic factor expression. Additionally, we implicate disruption of alternative splicing as a potential molecular mechanism underlying neuronal dysfunction in PWS. Transcriptomic analysis of the human hypothalamus may identify neural mechanisms involved in energy homeostasis and potential therapeutic targets for weight loss

Using the gut microbiota as a novel tool for examining colobine primate GI health

Primates of the Colobinae subfamily are highly folivorous. They possess a sacculated foregut and are believed to rely on a specialized gut microbiota to extract sufficient energy from their hard-to-digest diet. Although many colobines are endangered and would benefit from captive breeding programs, maintaining healthy captive populations of colobines can be difficult since they commonly suffer from morbidity and mortality due to gastrointestinal (GI) distress of unknown cause. While there is speculation that this GI distress may be associated with a dysbiosis of the gut microbiota, no study has directly examined the role of the gut microbiota in colobine GI health. In this study, we used high-throughput sequencing to examine the gut microbiota of three genera of colobines housed at the San Diego Zoo: doucs (Pygathrix) (N=7), colobus monkeys (Colobus) (N=4), and langurs (Trachypithecus) (N=5). Our data indicated that GI-healthy doucs, langurs, and colobus monkeys possess a distinct gut microbiota. In addition, GI-unhealthy doucs exhibited a different gut microbiota compared to GI-healthy individuals, including reduced relative abundances of anti-inflammatory Akkermansia. Finally, by comparing samples from wild and captive Asian colobines, we found that captive colobines generally exhibited higher relative abundances of potential pathogens such as Desulfovibrio and Methanobrevibacter compared to wild colobines, implying an increased risk of gut microbial dysbiosis. Together, these results suggest an association between the gut microbiota and GI illness of unknown cause in doucs. Further studies are necessary to corroborate these findings and determine cause-and-effect relationships. Additionally, we found minimal variation in the diversity and composition of the gut microbiota along the colobine GI tract, suggesting that fecal samples may be sufficient for describing the colobine gut microbiota. If these findings can be validated in wild individuals, it will facilitate the rapid expansion of colobine gut microbiome research