219 research outputs found

    Do doorways really matter : investigating memory benefits of event segmentation in a virtual learning environment

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    Event segmentation allows the flow of information experienced in life to be partitioned into distinct episodes, facilitating understanding of the world, action within it, and the ability to store information in memory. One basis on which experiences are segmented is the presence of physical boundaries, such as walking through doorways. Previous findings have shown that event segmentation has a significant influence on memory, with better memory for events occurring within a single boundary (compared to events that cross boundaries). By manipulating the features of boundaries and the amount of information presented between boundaries the present research investigates the nature of event boundaries. We make use of a virtual learning environment to present lists of words in virtual rooms, testing memory for the word lists as a function of the presence or absence of spatial-temporal gaps and physical boundaries during encoding (i.e., by maintaining participants within individual rooms or moving them through doorways between rooms). Across four experiments, we show that segmenting information with spatial-temporal gaps results in an increase in clustering (reflecting the structure imposed at encoding) an increase in the number of words remembered during later tests of episodic recall (a memory benefit) and an increase in recalling the words in the order of presentation. Importantly, however, the data show that the presence of doorways is not required for event segmentation to benefit memory: increases in clustering, memory for temporal order and recall performance were found with temporal gaps alone. Furthermore, the results suggest that episodic memory may be optimised if the amount of information between boundaries can be maintained within working memory. We discuss the implications of the findings for Event Segmentation Theory and propose an alternative theoretical account of the episodic memory benefits based on temporal clustering. [Abstract copyright: Copyright © 2020 Elsevier B.V. All rights reserved.]PostprintPeer reviewe

    Two new \u3ci\u3eVaejovis\u3c/i\u3e C.L. Koch 1836 from highlands of the Sierra Madre Occidental, Durango, Mexico (Scorpiones, Vaejovidae)

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    Two new species of the mexicanus group of Vaejovis C.L. Koch are described from the Madrean pine-oak forests of the Sierra Madre Occidental in the state of Durango, Mexico. These species, Vaejovis sierrae sp. nov. and Vaejovis mcwesti sp. nov., are distinguished from each other and the only other species of the mexicanus group known from this mountain range, Vaejovis montanus Graham and Bryson, by morphometrics, carinal development of the pedipalps, granulation of the metasoma, and body size. A key to the species of the mexicanus group from the Sierra Madre Occidental is provided

    Escape from human monoclonal antibody neutralization affects in vitro and in vivo fitness of severe acute respiratory syndrome coronavirus

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    Background. Severe acute respiratory syndrome (SARS) emerged as a human disease in 2002. Detailed phylogenetic analysis and epidemiologic studies have suggested that the SARS Coronavirus (SARS-CoV) originated from animals. The spike (S) glycoprotein has been identified as a major target of protective immunity and contains ≥3 regions that are targeted by neutralizing antibodies in the S1 and S2 domains. We previously characterized a panel of neutralizing human monoclonal antibodies (MAbs), but the majority of epitopes recognized by the MAbs remain unknown. Methods. In the present study, we generated neutralization escape mutants and studied the effect of these neutralization escape mutations on human and animal receptor usage as well as on in vitro and in vivo fitness. Results. Distinct but partially overlapping sets of amino acids were identified that are critical to the binding of MAbs with differential neutralization profiles. We also identified possible interactions between the S1 and S2 domains of the SARS-CoV S glycoprotein. Finally, we showed that escape from neutralization usually attenuates SARS-CoV infection. Conclusions. These data provide a mechanism for overcoming neutralization escape by use of broadly crossreactive cocktails of cross-neutralizing MAbs that recognize residues within the receptor-binding domain that are critical for virus replication and virulence

    Fivefold helically corrugated waveguide for high-power w-band gyro-devices and pulse compression

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    The design, simulation, manufacture and measurement of a W-band five-fold (5F) helically corrugated waveguide (HCW) is reported. The 5F HCW is based on the coupling of the traveling TE31 and near cut-off TE22 modes to create an operating eigenwave. The fabricated test structure has circular waveguide ports and features elliptical polariser sections and broadband TE11 to TE31 mode converters on either side of the 5F HCW. The optimised mode converter design, based on a four-fold (4F) HCW, has a predicted power conversion efficiency greater than 90% from 89 to 102.5 GHz, and 96% peak efficiency at 94 GHz. The optimization of the 5F HCW geometry produced an eigenwave suitable for gyro-devices, but the optimization could equally well have been directed to applications such as pulse compression and microwave undulators. Analysis of simulated electric field profiles showed that the propagating power in the 5F HCW was increased by a factor of 6 over that in the 3F HCW at equivalent peak electric field strength. This is due to the larger diameter of the waveguide. Test structures were manufactured through a combination of precision machining of a sacrificial mandrel, copper growth by electroforming followed by removal of the aluminium mandrel by chemically etching. Measurements of the 5F HCW structure’s dispersion showed excellent agreement with the prediction over the design range of 90 to 98 GHz

    Physiological Benefits of Being Small in a Changing World: Responses of Coho Salmon (Oncorhynchus kisutch) to an Acute Thermal Challenge and a Simulated Capture Event

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    Evidence is building to suggest that both chronic and acute warm temperature exposure, as well as other anthropogenic perturbations, may select for small adult fish within a species. To shed light on this phenomenon, we investigated physiological and anatomical attributes associated with size-specific responses to an acute thermal challenge and a fisheries capture simulation (exercise+air exposure) in maturing male coho salmon (Oncorhynchus kisutch). Full-size females were included for a sex-specific comparison. A size-specific response in haematology to an acute thermal challenge (from 7 to 20°C at 3°C h−1) was apparent only for plasma potassium, whereby full-size males exhibited a significant increase in comparison with smaller males (‘jacks’). Full-size females exhibited an elevated blood stress response in comparison with full-size males. Metabolic recovery following exhaustive exercise at 7°C was size-specific, with jacks regaining resting levels of metabolism at 9.3±0.5 h post-exercise in comparison with 12.3±0.4 h for full-size fish of both sexes. Excess post-exercise oxygen consumption scaled with body mass in male fish with an exponent of b = 1.20±0.08. Jacks appeared to regain osmoregulatory homeostasis faster than full-size males, and they had higher ventilation rates at 1 h post-exercise. Peak metabolic rate during post-exercise recovery scaled with body mass with an exponent of b∼1, suggesting that the slower metabolic recovery in large fish was not due to limitations in diffusive or convective oxygen transport, but that large fish simply accumulated a greater ‘oxygen debt’ that took longer to pay back at the size-independent peak metabolic rate of ∼6 mg min−1 kg−1. Post-exercise recovery of plasma testosterone was faster in jacks compared with full-size males, suggesting less impairment of the maturation trajectory of smaller fish. Supporting previous studies, these findings suggest that environmental change and non-lethal fisheries interactions have the potential to select for small individuals within fish populations over time

    Variations in the Hemagglutinin of the 2009 H1N1 Pandemic Virus: Potential for Strains with Altered Virulence Phenotype?

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    A novel, swine-origin influenza H1N1 virus (H1N1pdm) caused the first pandemic of the 21st century. This pandemic, although efficient in transmission, is mild in virulence. This atypical mild pandemic season has raised concerns regarding the potential of this virus to acquire additional virulence markers either through further adaptation or possibly by immune pressure in the human host. Using the mouse model we generated, within a single round of infection with A/California/04/09/H1N1 (Ca/04), a virus lethal in mice—herein referred to as mouse-adapted Ca/04 (ma-Ca/04). Five amino acid substitutions were found in the genome of ma-Ca/04: 3 in HA (D131E, S186P and A198E), 1 in PA (E298K) and 1 in NP (D101G). Reverse genetics analyses of these mutations indicate that all five mutations from ma-Ca/04 contributed to the lethal phenotype; however, the D131E and S186P mutations—which are also found in the 1918 and seasonal H1N1 viruses—in HA alone were sufficient to confer virulence of Ca/04 in mice. HI assays against H1N1pdm demonstrate that the D131E and S186P mutations caused minor antigenic changes and, likely, affected receptor binding. The rapid selection of ma-Ca/04 in mice suggests that a virus containing this constellation of amino acids might have already been present in Ca/04, likely as minor quasispecies

    Protocol for Northern Ireland Caries Prevention in Practice Trial (NIC-PIP) trial: a randomised controlled trial to measure the effects and costs of a dental caries prevention regime for young children attending primary care dental services

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    <p>Abstract</p> <p>Background</p> <p>Dental caries is a persistent public health problem with little change in the prevalence in young children over the last 20 years. Once a child contracts the disease it has a significant impact on their quality of life. There is good evidence from Cochrane reviews including trials that fluoride varnish and regular use of fluoride toothpaste can prevent caries.</p> <p>The Northern Ireland Caries Prevention in Practice Trial (NIC-PIP) trial will compare the costs and effects of a caries preventive package (fluoride varnish, toothpaste, toothbrush and standardised dental health education) with dental health education alone in young children.</p> <p>Methods/Design</p> <p>A randomised controlled trial on children initially aged 2 and 3 years old who are regular attenders at the primary dental care services in Northern Ireland. Children will be recruited and randomised in dental practices. Children will be randomised to the prevention package of both fluoride varnish (twice per year for three years), fluoride toothpaste (1,450 ppm F) (supplied twice per year), a toothbrush (supplied twice a year) or not; both test and control groups receive standardised dental health education delivered by the dentist twice per year. Randomisation will be conducted by the Belfast Trust Clinical Research Support Centre ([CRSC] a Clinical Trials Unit).</p> <p>1200 participants will be recruited from approximately 40 dental practices. Children will be examined for caries by independent dental examiners at baseline and will be excluded if they have caries. The independent dental examiners will examine the children again at 3 years blinded to study group.</p> <p>The primary end-point is whether the child develops caries (cavitation into dentine) or not over the three years. One secondary outcome is the number of carious surfaces in the primary dentition in children who experience caries. Other secondary outcomes are episodes of pain, extraction of primary teeth, other adverse events and costs which will be obtained from parental questionnaires.</p> <p>Discussion</p> <p>This is a pragmatic trial conducted in general dental practice. It tests a composite caries prevention intervention, which represents an evidence based approach advocated by current guidance from the English Department of Health which is feasible to deliver to all low risk (caries free) children in general dental practice. The trial will provide valuable information to policy makers and clinicians on the costs and effects of caries prevention delivered to young children in general dental practice.</p> <p>Trial registration</p> <p>EudraCT No: 2009 - 010725 - 39</p> <p>ISRCTN: <a href="http://www.controlled-trials.com/ISRCTN36180119">ISRCTN36180119</a></p> <p>Ethics Reference No: 09/H1008/93:</p
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