Miracle-dz/UniFAR-FTUs huggingface dataset:
Place Cell Networks in Pre-weanling Rats Show Associative Memory Properties from the Onset of Exploratory Behavior

Place cells are hippocampal pyramidal cells that are active when an animal visits a restricted area of the environment, and collectively their activity constitutes a neural representation of space. Place cell populations in the adult rat hippocampus display fundamental properties consistent with an associative memory network: the ability to 1) generate new and distinct spatial firing patterns when encountering novel spatial contexts or changes in sensory input (“remapping”) and 2) reinstate previously stored firing patterns when encountering a familiar context, including on the basis of an incomplete/degraded set of sensory cues (“pattern completion”). To date, it is unknown when these spatial memory responses emerge during brain development. Here, we show that, from the age of first exploration (postnatal day 16) onwards, place cell populations already exhibit these key features: they generate new representations upon exposure to a novel context and can reactivate familiar representations on the basis of an incomplete set of sensory cues. These results demonstrate that, as early as exploratory behaviors emerge, and despite the absence of an adult-like grid cell network, the developing hippocampus processes incoming sensory information as an associative memory network.
Is prefrontal cortex necessary for the storage and acquisition of relational concepts?

Abstract The ability to make analogies requires building higher order relations and so keeping track of multiple independently varying dimensions of the concepts being compared. Frontal cortex may be well suited to support this type of function, as Speed's review makes clear. However, Speed goes further in arguing that PFC neurons necessarily support the storage and acquisition of relational concepts. This claim is evaluated in the context of broader perspectives on storage and acquisition of semantic knowledge.
Levels of Interpersonal Concerns and Social Functioning in Early Adolescent Boys and Girls

Previous research has shown that the Interpersonal Concerns factor of the Depressive Experiences Questionnaire (DEQ; Blatt, D'Affliti, & Quinlan, 1976, 1979; Depressive Experiences Questionnaire for Adolescent [DEQ-A]; Blatt, Schaffer, Bers, & Quinlan, 1992) assesses 2 levels of interpersonal relatedness in young adults and older adolescents: neediness and relatedness. However, studies investigating the relation of the DEQ and DEQ-A with social functioning have not used the Neediness and Relatedness subscales of the Interpersonal Concerns factor. This study investigated (a) whether the Neediness and Relatedness subscales can be differentiated in a sample of early adolescents and (b) how the 2 subscales are differentially associated with indexes of social functioning. Results indicate that this differentiation of Neediness and Relatedness, and their associations with social functioning, emerges in early adolescence, especially for girls.
Estimating the distance to a monotone function

In standard property testing, the task is to distinguish between objects that have a property 𝒫 and those that are ε‐far from 𝒫, for some ε > 0. In this setting, it is perfectly acceptable for the tester to provide a negative answer for every input object that does not satisfy 𝒫. This implies that property testing in and of itself cannot be expected to yield any information whatsoever about the distance from the object to the property. We address this problem in this paper, restricting our attention to monotonicity testing. A function f : {1,…,n} ↦ R is at distance εf from being monotone if it can (and must) be modified at εfn places to become monotone. For any fixed δ > 0, we compute, with probability at least 2/3, an interval [(1/2 − δ)ε,ε] that encloses εf. The running time of our algorithm is O(εf−1 log log εf− 1 log n), which is optimal within a factor of loglog εf−1 and represents a substantial improvement over previous work. We give a second algorithm with an expected running time of O(εf−1 log nlog log log n). Finally, we extend our results to multivariate functions. © 2007 Wiley Periodicals, Inc. Random Struct. Alg. , 2007
Friction and Wear Characteristics of a Modified Composite Solid Lubricant Plasma Spray Coating

LCR304 is a solid lubricant coating composed of Ni-10Cr, Cr2O3, BaF2-CaF2 and Ag and developed for dimensional stability in high temperature air. This coating is a modification of PS304, which differs in that the Ni-Cr constituent contains 20wt% Cr. The tribological characteristics of LCR304 were evaluated by pin-on-disk and foil air bearing rig testing from 25 to 650 C and compared to previous test results with PS304. For both tests, the friction coefficient decreased as temperature increased from 25 to 650 C. Wear generally decreased with increasing temperature for all pin-on-disk tests. LCR304 coated components produced the least wear of Inconel X-750 counterface materials at 427 and 650 C. These results indicate that the LCR304 coating has potential as a replacement for PS304 in, for example, low cycle (minimum wear) applications where dimensional stability is imperative.
Fitness Trade-Offs Determine the Role of the Molecular Chaperonin GroEL in Buffering Mutations

Molecular chaperones fold many proteins and their mutated versions in a cell and can sometimes buffer the phenotypic effect of mutations that affect protein folding. Unanswered questions about this buffering include the nature of its mechanism, its influence on the genetic variation of a population, the fitness trade-offs constraining this mechanism, and its role in expediting evolution. Answering these questions is fundamental to understand the contribution of buffering to increase genetic variation and ecological diversification. Here, we performed experimental evolution, genome resequencing, and computational analyses to determine the trade-offs and evolutionary trajectories of Escherichia coli expressing high levels of the essential chaperonin GroEL. GroEL is abundantly present in bacteria, particularly in bacteria with large loads of deleterious mutations, suggesting its role in mutational buffering. We show that groEL overexpression is costly to large populations evolving in the laboratory, leading to groE expression decline within 66 generations. In contrast, populations evolving under the strong genetic drift characteristic of endosymbiotic bacteria avoid extinction or can be rescued in the presence of abundant GroEL. Genomes resequenced from cells evolved under strong genetic drift exhibited significantly higher tolerance to deleterious mutations at high GroEL levels than at native levels, revealing that GroEL is buffering mutations in these cells. GroEL buffered mutations in a highly diverse set of proteins that interact with the environment, including substrate and ion membrane transporters, hinting at its role in ecological diversification. Our results reveal the fitness trade-offs of mutational buffering and how genetic variation is maintained in populations.
Electrical properties of viscose-kraft fibre mixtures

ABSTRACT We used mixture handsheets of pine kraft and viscose fibres to study how density and moisture content affect the electrical properties of paper. When the viscose content increased from 0% to 70%, paper density decreased from 650 kg/m 3 to 280 kg/m 3 . The effect of density on the dielectric constant of paper was consistent with the Clausius-Mossotti relation provided that the relative humidity was low or the measurement frequency high. Under these conditions, the water absorbed by paper had little effect on the dielectric constant or dielectric loss factor. When the moisture content of paper exceeded a certain limit, the dielectric constant began to increase rapidly. Presumably this happened because some of the adsorbed water resembles bulk water in its electrical properties and therefore has a much higher dielectric constant than dry cellulose. The threshold moisture content increased with increasing measurement frequency. The viscose fibres absorbed 2-3%-units more water than the kraft fibres at any given relative humidity. In spite of this, increasing the viscose content decreased the dielectric constant of paper. This indicates that the water molecules are more closely bonded and have less freedom to rotate in viscose fibres than in kraft fibres. The dielectric loss term was practically zero at low moisture contents, approximately below the same threshold that governs the dielectric constant. The dc resistivity decreased as an exponential function of increasing moisture content, but viscose fibres gave a lower conductivity than kraft fibres at a fixed moisture content. Hence, the water absorbed by viscose fibres influenced the electrical properties of paper in all respects less than the water absorbed by kraft fibres.
Salicylic acid modulates colonization of the root microbiome by specific bacterial taxa

Immune signals shape root communities To thwart microbial pathogens aboveground, the plant Arabidopsis turns on defensive signaling using salicylic acid. In Arabidopsis plants with modified immune systems, Lebeis et al. show that bacterial communities change in response to salicylic acid signaling in the root zone as well (see the Perspective by Haney and Ausubel). Abundance of some root-colonizing bacterial families increased at the expense of others, partly as a function of whether salicylic acid was used as an immune signal or as a carbon source for microbial growth. Science, this issue p. 860; see also p. 788 Bacteria that are endosymbiotic with the plant root respond to changes in the plant’s signaling status. [Also see Perspective by Haney and Ausubel] Immune systems distinguish “self” from “nonself” to maintain homeostasis and must differentially gate access to allow colonization by potentially beneficial, nonpathogenic microbes. Plant roots grow within extremely diverse soil microbial communities but assemble a taxonomically limited root-associated microbiome. We grew isogenic Arabidopsis thaliana mutants with altered immune systems in a wild soil and also in recolonization experiments with a synthetic bacterial community. We established that biosynthesis of, and signaling dependent on, the foliar defense phytohormone salicylic acid is required to assemble a normal root microbiome. Salicylic acid modulates colonization of the root by specific bacterial families. Thus, plant immune signaling drives selection from the available microbial communities to sculpt the root microbiome.
Retinal Oscillations Carry Visual Information to Cortex

Thalamic relay cells fire action potentials that transmit information from retina to cortex. The amount of information that spike trains encode is usually estimated from the precision of spike timing with respect to the stimulus. Sensory input, however, is only one factor that influences neural activity. For example, intrinsic dynamics, such as oscillations of networks of neurons, also modulate firing pattern. Here, we asked if retinal oscillations might help to convey information to neurons downstream. Specifically, we made whole-cell recordings from relay cells to reveal retinal inputs (EPSPs) and thalamic outputs (spikes) and then analyzed these events with information theory. Our results show that thalamic spike trains operate as two multiplexed channels. One channel, which occupies a low frequency band (<30 Hz), is encoded by average firing rate with respect to the stimulus and carries information about local changes in the visual field over time. The other operates in the gamma frequency band (40–80 Hz) and is encoded by spike timing relative to retinal oscillations. At times, the second channel conveyed even more information than the first. Because retinal oscillations involve extensive networks of ganglion cells, it is likely that the second channel transmits information about global features of the visual scene.
Mannose‐binding lectin levels in children with asthma

Mannose‐binding lectin (mbl), one of the important components of innate immunity, can activate the lectin pathway of the complement system. After binding mannose containing carbohydrate structures of foreign antigen, mbl initiates and regulates the inflammatory responses. Asthma is a complex inflammatory disease of the lung involving many components of the immune system. Our objective was to investigate the serum mbl levels of asthmatic children in comparison with healthy controls. Serum mbl levels were determined by nephelometric assay in 72 asthmatic children (5–15 yr old) and 30 healthy age‐matched controls. Mbl levels of asthmatic children were measured both during acute attack and after complete remission. There was no significant difference between the mbl levels during acute attack (median 4.1 mg/l) or quiescence of symptoms (median 3.6 mg/l). Serum mbl levels both during acute attack or quiescence of symptoms was significantly higher in asthmatic children than in the healthy controls (median 2.8 mg/l, p < 0.0001 for each). Furthermore, mbl levels of asthmatic children positively correlated with peripheral blood eosinophils (r = 0.377, p < 0.001), which is a systemic component of airway inflammation in asthma. Our findings indicate that mbl may be implicated in the pathogenesis of asthma by contributing to airway inflammation or by increasing the risk of developing asthma.
Mast Cell-Dependent Control of Giardia lamblia Infections in Mice

ABSTRACT Mast cells are important for protective immunity to intestinal helminth infections and as mediators of allergic disease. Their role in protozoan infections is less well described. We have therefore analyzed mast cell responses and parasite control in mice infected with the protozoan Giardia lamblia. We also measured immunoglobulin A (IgA) responses to the parasite, as IgA can have a protective role in this model. c-kitw/wv mice failed to make parasite-specific IgA, mount a mast cell response, or eliminate the infection. Anti-c-kit-treated C57BL/6 mice had normal IgA responses, lacked mast cell responses, had reduced interleukin-6 (IL-6) mRNA in the small intestine, and failed to control the infection within 10 days. IL-9-deficient mice had a significant but reduced mast cell response and still controlled the infection within 2 weeks. Interestingly, IL-6-deficient mice had enhanced mast cell responses yet failed to rapidly control the infection. However, prevention of mast cell responses in IL-6-deficient mice by anti-c-kit treatment did not lead to parasite elimination. Both IL-6- and IL-9-deficient mice had normal IgA production. IL-6-deficient mice had significant serum levels of mast cell mediators, histamine and mast cell protease 1, following infection. Together, these results show that mast cells are important for the rapid control of Giardia infections in mice. Furthermore, they show that IL-6 is not necessary for these mast cell responses. Instead, they suggest that mast cell production of IL-6 appears to be important for control of this infection.
Diversity sustains an evolving network

We study an evolutionary model of a complex system that evolves under catalytic dynamics and Darwinian selection and exhibits spontaneous growth, stasis and then a collapse of its structure. We find that the typical lifetime of the system increases sharply with the diversity of its components or species. We also find that the prime reason for crashes is a naturally occurring internal fragility of the system. This fragility is captured in the network organizational character and is related to a reduced multiplicity of pathways or feedback loops between its components. These results apply to several generalizations of the model as well. This work suggests new parameters for understanding the robustness of evolving molecular networks, ecosystems, societies and markets.
Detecting Genetic Introgression: High Levels of Intersubspecific Recombination Found in Xylella fastidiosa in Brazil

ABSTRACT Documenting the role of novel mutation versus homologous recombination in bacterial evolution, and especially in the invasion of new hosts, is central to understanding the long-term dynamics of pathogenic bacteria. We used multilocus sequence typing (MLST) to study this issue in Xylella fastidiosa subsp. pauca from Brazil, a bacterium causing citrus variegated chlorosis (CVC) and coffee leaf scorch (CLS). All 55 citrus isolates typed (plus one coffee isolate) defined three similar sequence types (STs) dominated by ST11 (85%), while the remaining 22 coffee isolates defined two STs, mainly ST16 (74%). This low level of variation masked unusually large allelic differences (>1% divergence with no intermediates) at five loci (leuA, petC, malF, cysG, and holC). We developed an introgression test to detect whether these large differences were due to introgression via homologous recombination from another X. fastidiosa subspecies. Using additional sequencing around these loci, we established that the seven randomly chosen MLST targets contained seven regions of introgression totaling 2,172 bp of 4,161 bp (52%), only 409 bp (10%) of which were detected by other recombination tests. This high level of introgression suggests the hypothesis that X. fastidiosa subsp. pauca became pathogenic on citrus and coffee (crops cultivated in Brazil for several hundred years) only recently after it gained genetic variation via intersubspecific recombination, facilitating a switch from native hosts. A candidate donor is the subspecies infecting plum in the region since 1935 (possibly X. fastidiosa subsp. multiplex). This hypothesis predicts that nonrecombinant native X. fastidiosa subsp. pauca (not yet isolated) does not cause disease in citrus or coffee.
Current State of Pancreas Preservation and Implications for DCD Pancreas Transplantation

One of the main factors limiting potential uptake of pancreas transplantation, particularly in the United Kingdom, is the shortage of grafts. There has therefore been a recent expansion, particularly in the United Kingdom, in the utilization of grafts from donation after cardiac death (DCD) donors. These grafts are subjected to a greater ischemic insult and are arguably at higher risk of poor functional outcome. Although conventional preservation techniques may be adequate for donation after brain death (DBD) and low-risk DCD pancreases, as the number of DCD pancreas transplants increase and the threshold for rejecting organs decreases, the importance of optimal preservation techniques is going to increase. Over recent years, there have been significant advances in preservation techniques for DCD kidneys, improving the outcome of these marginal grafts. However, the use of such techniques for pancreas preservation is extremely limited and mainly historical. This overview describes the background and results of the established method of pancreas preservation for DBD, namely, cold static storage, and describes the use of the two-layer method. It also reviews pulsatile machine perfusion and normothermic perfusion for pancreas preservation techniques, which have shown promise in the preservation of DCD kidney grafts. The use of these techniques in pancreas preservation is predominantly historical but warrants reevaluation as to the feasibility of applying these techniques to DCD pancreas grafts not only for preservation but also for viability assessment. Further areas for development of pancreas preservation are discussed.
Positive selection on the killer whale mitogenome

Mitochondria produce up to 95 per cent of the eukaryotic cell's energy. The coding genes of the mitochondrial DNA may therefore evolve under selection owing to metabolic requirements. The killer whale, Orcinus orca, is polymorphic, has a global distribution and occupies a range of ecological niches. It is therefore a suitable organism for testing this hypothesis. We compared a global dataset of the complete mitochondrial genomes of 139 individuals for amino acid changes that were associated with radical physico-chemical property changes and were influenced by positive selection. Two such selected non-synonymous amino acid changes were found; one in each of two ecotypes that inhabit the Antarctic pack ice. Both substitutions were associated with changes in local polarity, increased steric constraints and α-helical tendencies that could influence overall metabolic performance, suggesting a functional change.
Posthypoxic treatment with felbamate is neuroprotective in a rat model of hypoxia‐ischemia

Felbamate, a novel dicarbamate anticonvulsant that blocks the glycine site of the N-methyl-D-aspartate receptor and protects the hippocampal slice from hypoxic damage, shows remarkably low toxicity in animals and in humans. Since most treatment of human cerebral ischemia will have to be delivered after the insult, we investigated the neuroprotective potency of post hoc felbamate in rat pups with bilateral carotid ligations exposed to an atmosphere of 6.5% O2 for 1 hour. Brain temperature was unaffected by surgery, hypoxia, or felbamate. Neuroprotection was greatest at 300 mg/kg, less effective at 200 and 400 mg/kg, and ineffective at 100 mg/kg. Post hoc felbamate (300 mg/kg) reduced the volume of infarction from 67% ± 7% of neocortex in unmedicated rats to 32% ± 8%, 51% ± 12%, 38% ± 19%, and 53% ± 10% when given 0, 1, 2, and 4 hours after hypoxic exposure, respectively. By 6 hours, post hoc protection was no longer significant. Delayed neuronal necrosis in hippocampal granule cells was reduced from 156 ± 33 neurons to 12 ± 7 (0 hour, p < 0.01) and 37 ± 17 (1 hour, p < 0.05). These effects were obtained at plasma concentrations (60 to 120 mg/ml) that have occasionally been reached without serious toxicity in human anticonvulsant trials. These data suggest that, in this animal model, felbamate given after a hypoxic-ischemic insult is effective in reducing cerebral infarction and extremely effective in preventing delayed neuronal necrosis, but that the window of opportunity for post hoc treatment is only 1 to 4 hours.
Staphylococcus aureus Isolated in Cases of Impetigo Produces Both Epidermolysin A or B and LukE-LukD in 78% of 131 Retrospective and Prospective Cases

ABSTRACT Clinical symptoms of impetigo and staphylococcal scalded skin syndrome may not only be expressed as the splitting of cell layers within the epidermis but are often accompanied by some localized inflammation. Toxin patterns of Staphylococcus aureusisolates originating from patients with impetigo and also from those with other primary and secondary skin infections in a retrospective isolate collection in France and a prospective isolate collection in French Guiana revealed a significant association (75% of the cases studied) of impetigo with production of at least one of the epidermolysins A and B and the bicomponent leucotoxin LukE-LukD (P < 0.001). However, most of the isolates were able to produce one of the nonubiquitous enterotoxins. Pulsed-field gel electrophoresis (PFGE) of genomic DNA hydrolyzed withSmaI showed a polymorphism of the two groups of isolates despite the fact that endemic clones were suspected in French Guiana and France. The combination of toxin patterns with PFGE fingerprinting may provide further discrimination among isolates defined in a given cluster or a given pulsotype and account for a specific virulence. The new association of toxins with a clinical syndrome may reveal principles of the pathological process.