1,024 research outputs found

    Chronic voluntary alcohol consumption causes persistent cognitive deficits and cortical cell loss in a rodent model

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    Chronic alcohol use is associated with cognitive decline that impedes behavioral change during rehabilitation. Despite this, addiction therapy does not address cognitive deficits, and there is poor understanding regarding the mechanisms that underlie this decline. We established a rodent model of chronic voluntary alcohol use to measure ensuing cognitive effects and underlying pathology. Rats had intermittent access to alcohol or an isocaloric solution in their home cage under voluntary 2-bottle choice conditions. In Experiments 1 and 2 cognition was assessed using operant touchscreen chambers. We examined performance in a visual discrimination and reversal task (Experiment 1), and a 5-choice serial reaction time task (Experiment 2). For Experiment 3, rats were perfused immediately after cessation of alcohol access period, and volume, cell density and microglial populations were assessed in the prefrontal cortex and striatum. Volume was assessed using the Cavalieri probe, while cell and microglial counts were estimated using unbiased stereology with an optical fractionator. Alcohol-exposed and control rats showed comparable acquisition of pairwise discrimination; however, performance was impaired when contingencies were reversed indicating reduced behavioral flexibility. When tested in a 5-choice serial reaction time task alcohol-exposed rats showed increased compulsivity and increased attentional bias towards a reward associated cue. Consistent with these changes, we observed decreased cell density in the prefrontal cortex. These findings confirm a detrimental effect of chronic alcohol and establish a model of alcohol-induced cognitive decline following long-term voluntary intake that may be used for future intervention studies

    The consequences of nuclear electron capture in core collapse supernovae

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    The most important weak nuclear interaction to the dynamics of stellar core collapse is electron capture, primarily on nuclei with masses larger than 60. In prior simulations of core collapse, electron capture on these nuclei has been treated in a highly parameterized fashion, if not ignored. With realistic treatment of electron capture on heavy nuclei come significant changes in the hydrodynamics of core collapse and bounce. We discuss these as well as the ramifications for the post-bounce evolution in core collapse supernovae.Comment: Accepted by PRL, 5 pages, 2 figure

    A national survey of supervised toothbrushing programmes in England

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    Introduction Supervised toothbrushing programmes (STPs) are a cost-effective public health intervention, reducing tooth decay and health inequalities in children. However, the uptake of STPs in England is unknown. This study aimed to establish the current provision of STPs across England and summarise the barriers and facilitators to their implementation. Methods An online survey was sent to dental public health consultants, local authority (LA) oral health leads, and public health practitioners across England. Quantitative data were analysed using descriptive statistics. Barriers and facilitators were analysed using the Consolidated Framework for Implementation Research. Results Information was received for 141 LAs across England. Approximately half implemented an STP (n = 68/141). Most STPs were commissioned by LAs (n = 44/68) and adopted a targeted approach (n = 54/68). Barriers to implementation were: 1) acquiring funding; 2) poor communication and engagement between LAs, oral health providers and settings; 3) oral health not a priority; 4) logistically challenging to implement; and 5) lack of capacity. Facilitators were: 1) an integrated and mandated public health approach; 2) collaboration and ongoing support between LAs, oral health providers, and settings; 3) clarity of guidance; 4) flexible approach to delivery; 5) adequate available resources; and 6) ownership and empowerment of setting staff. Conclusion The current provision of STPs is varied, and although there are challenges to their implementation, there are also areas of good practice where these challenges have been overcome

    Effect of three wound dressings on infection, healing comfort, and cost in patients with sternotomy wounds - a randomized trial

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    Study objective: To compare three dressing types in terms of their ability to protect against infection and promote healing, patient comfort, and cost-effectiveness.Design: Prospective, randomized controlled trial.Setting: Major metropolitan, academically affiliated, tertiary referral center.Patients: Seven hundred thirty-seven patients were randomized to receive a dry absorbent dressing (n = 243) [Primapore; Smith &amp; Nephew; Sydney, NSW, Australia], a hydrocolloid dressing (n = 267) [Duoderm Thin ConvaTec; Mulgrave, VIC, Australia], or a hydroactive dressing (n = 227) [Opsite; Smith &amp; Nephew] in the operating theater on skin closure.Results: There was no difference in the rate of wound infection or wound healing between treatment groups. The Primapore dressing was the most comfortable and cost-effective dressing option for the sternotomy wound. Duoderm Thin dressings were associated with increased wound exudate (p &lt; 0.001), poor dressing integrity (p &lt; 0.001), more frequent dressing changes (p &lt; 0.001), more discomfort with removal (p &lt; 0.05), and increased cost (p &lt; 0.001).Conclusions: In the context of no additional benefit for the prevention of wound infection or the rate of wound healing for any of the three dressing products examined, dry absorbent dressings are the most comfortable and cost-effective products for sternotomy wounds following cardiac surgery.<br /

    Surface features, rotation and atmospheric variability of ultra cool dwarfs

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    Photometric I band light curves of 21 ultra cool M and L dwarfs are presented. Variability with amplitudes of 0.01 to 0.055 magnitudes (RMS) with typical timescales of an hour to several hours are discovered in half of these objects. Periodic variability is discovered in a few cases, but interestingly several variable objects show no significant periods, even though the observations were almost certainly sensitive to the expected rotation periods. It is argued that in these cases the variability is due to the evolution of the surface features on timescales of a few hours. This is supported in the case of 2M1145 for which no common period is found in two separate light curves. It is speculated that these features are photospheric dust clouds, with their evolution possibly driven by rotation and turbulence. An alternative possibility is magnetically-induced surface features. However, chromospheric activity undergoes a sharp decrease between M7 and L1, whereas a greater occurrence of variability is observed in objects later than M9, lending support to the dust interpretation.Comment: To appear in "Ultracool Dwarf Stars" (Lecture Notes in Physics), H.R.A. Jones, I. Steele (eds), Springer-Verlag, 2001. Also available from http://www.mpia-hd.mpg.de/homes/calj/ultra.htm

    The equation of state and composition of hot, dense matter in core-collapse supernovae

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    The equation of state and composition of matter are calculated for conditions typical for pre-collapse and early collapse stages in core collapse supernovae. The composition is evaluated under the assumption of nuclear statistical equilibrium, when the matter is considered as an `almost' ideal gas with corrections due to thermal excitations of nuclei, to free nucleon degeneracy, and to Coulomb and surface energy corrections. The account of these corrections allows us to obtain the composition for densities a bit below the nuclear matter density. Through comparisons with the equation of state (EOS) developed by Shen et al. we examine the approximation of one representative nucleus used in most of recent supernova EOS's. We find that widely distributed compositions in the nuclear chart are different, depending on the mass formula, while the thermodynamical quantities are quite close to those in the Shen's EOS.Comment: LaTeX 21 pages, 16 figure

    The Classification of T Dwarfs

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    We discuss methods for classifying T dwarfs based on spectral morphological features and indices. T dwarfs are brown dwarfs which exhibit methane absorption bands at 1.6 and 2.2 ÎĽm{\mu}m. Spectra at red optical (6300--10100 {\AA}) and near-infrared (1--2.5 ÎĽm{\mu}m) wavelengths are presented, and differences between objects are noted and discussed. Spectral indices useful for classification schemes are presented. We conclude that near-infrared spectral classification is generally preferable for these cool objects, with data sufficient to resolve the 1.17 and 1.25 ÎĽm{\mu}m K I doublets lines being most valuable. Spectral features sensitive to gravity are discussed, with the strength of the K-band peak used as an example. Such features may be used to derive a two-dimensional scheme based on temperature and mass, in analogy to the MK temperature and luminosity classes.Comment: 15 pages, 6 figures, conference proceedings for IAU Ultracool Dwarf Stars session, ed. I. Steele & H. Jone

    <i>Toxoplasma gondii</i> peptide ligands open the gate of the HLA class I binding groove

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    HLA class I presentation of pathogen-derived peptide ligands is essential for CD8+ T-cell recognition of Toxoplasma gondii infected cells. Currently, little data exist pertaining to peptides that are presented after T. gondii infection. Herein we purify HLA-A*02:01 complexes from T. gondii infected cells and characterize the peptide ligands using LCMS. We identify 195 T. gondii encoded ligands originating from both secreted and cytoplasmic proteins. Surprisingly, T. gondii ligands are significantly longer than uninfected host ligands, and these longer pathogen-derived peptides maintain a canonical N-terminal binding core yet exhibit a C-terminal extension of 1-30 amino acids. Structural analysis demonstrates that binding of extended peptides opens the HLA class I F' pocket, allowing the C-terminal extension to protrude through one end of the binding groove. In summary, we demonstrate that unrealized structural flexibility makes MHC class I receptive to parasite-derived ligands that exhibit unique C-terminal peptide extensions.Fil: McMurtrey, Curtis. University of Oklahoma; Estados UnidosFil: Trolle, Thomas. Technical University of Denmark; Dinamarca. La Jolla Institute for Allergy and Immunology; Estados UnidosFil: Sansom, Tiffany. University at Buffalo; Estados UnidosFil: Remesh, Soumya G.. La Jolla Institute for Allergy and Immunology; Estados UnidosFil: Kaever, Thomas. La Jolla Institute for Allergy and Immunology; Estados UnidosFil: Bardet, Wilfried. University of Oklahoma; Estados UnidosFil: Jackson, Kenneth. University of Oklahoma; Estados UnidosFil: McLeod, Rima. University of Chicago; Estados UnidosFil: Sette, Alessandro. La Jolla Institute for Allergy and Immunology; Estados UnidosFil: Nielsen, Morten. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - La Plata. Instituto de Investigaciones BiotecnolĂłgicas. Instituto de Investigaciones BiotecnolĂłgicas "Dr. RaĂşl AlfonsĂ­n" (sede ChascomĂşs). Universidad Nacional de San MartĂ­n. Instituto de Investigaciones BiotecnolĂłgicas. Instituto de Investigaciones BiotecnolĂłgicas "Dr. RaĂşl AlfonsĂ­n" (sede ChascomĂşs); Argentina. Technical University of Denmark; DinamarcaFil: Zajonc, Dirk M.. La Jolla Institute for Allergy and Immunology; Estados UnidosFil: Blader, Ira J. University at Buffalo; Estados UnidosFil: Peters, Bjoern. La Jolla Institute for Allergy and Immunology; Estados UnidosFil: Hildebrand, William. University of Oklahoma; Estados Unido

    MCMAS: an open-source model checker for the verification of multi-agent systems

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    We present MCMAS, a model checker for the verification of multi-agent systems. MCMAS supports efficient symbolic techniques for the verification of multi-agent systems against specifications representing temporal, epistemic and strategic properties. We present the underlying semantics of the specification language supported and the algorithms implemented in MCMAS, including its fairness and counterexample generation features. We provide a detailed description of the implementation. We illustrate its use by discussing a number of examples and evaluate its performance by comparing it against other model checkers for multi-agent systems on a common case study
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