281 research outputs found

    A stochastic neuronal model predicts random search behaviors at multiple spatial scales in C. elegans

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    Random search is a behavioral strategy used by organisms from bacteria to humans to locate food that is randomly distributed and undetectable at a distance. We investigated this behavior in the nematode Caenorhabditis elegans, an organism with a small, well-described nervous system. Here we formulate a mathematical model of random search abstracted from the C. elegans connectome and fit to a large-scale kinematic analysis of C. elegans behavior at submicron resolution. The model predicts behavioral effects of neuronal ablations and genetic perturbations, as well as unexpected aspects of wild type behavior. The predictive success of the model indicates that random search in C. elegans can be understood in terms of a neuronal flip-flop circuit involving reciprocal inhibition between two populations of stochastic neurons. Our findings establish a unified theoretical framework for understanding C. elegans locomotion and a testable neuronal model of random search that can be applied to other organisms

    First radial velocity results from the MINiature Exoplanet Radial Velocity Array (MINERVA)

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    The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated observatory of four 0.7m robotic telescopes fiber-fed to a KiwiSpec spectrograph. The MINERVA mission is to discover super-Earths in the habitable zones of nearby stars. This can be accomplished with MINERVA's unique combination of high precision and high cadence over long time periods. In this work, we detail changes to the MINERVA facility that have occurred since our previous paper. We then describe MINERVA's robotic control software, the process by which we perform 1D spectral extraction, and our forward modeling Doppler pipeline. In the process of improving our forward modeling procedure, we found that our spectrograph's intrinsic instrumental profile is stable for at least nine months. Because of that, we characterized our instrumental profile with a time-independent, cubic spline function based on the profile in the cross dispersion direction, with which we achieved a radial velocity precision similar to using a conventional "sum-of-Gaussians" instrumental profile: 1.8 m s1^{-1} over 1.5 months on the RV standard star HD 122064. Therefore, we conclude that the instrumental profile need not be perfectly accurate as long as it is stable. In addition, we observed 51 Peg and our results are consistent with the literature, confirming our spectrograph and Doppler pipeline are producing accurate and precise radial velocities.Comment: 22 pages, 9 figures, submitted to PASP, Peer-Reviewed and Accepte

    Environmental Fit: A Model for Assessing and Treating Problem Behavior Associated with Curricular Difficulties in Children with Autism Spectrum Disorders

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    Theoretical considerations suggest that problem behavior should increase when a child’s competency does not match the curricular demands of the environment (i.e., when there is poor environmental fit). In the present study, environmental fit was examined for six children with autism spectrum disorders. Results indicated that the children exhibited high rates of problem behavior associated with poor motor or academic competency. Curricular modifications resulted in (a) a decrease in the level of problem behavior, (b) an increase in the percentage of task steps completed correctly, and (c) improved affect. Adults who worked with the children reported ease of intervention techniques. The concept of environmental fit and its usefulness in guiding both assessment of and intervention for problem behavior are discussed

    Prospective Study on Several Urinary Biomarkers as Indicators of Renal Damage in Children with CAKUT

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    Purpose The aim of the study was to investigate urinary levels of monocyte chemotactic protein-1 (MCP-1), epidermal growth factor (EGF), β-2-microglobulin (β2M), and FAS-ligand (FAS-L) in children with congenital anomalies of kidney and urinary tract (CAKUT) disease at risk of developing glomerular hyperfiltration syndrome. For this reason, we selected patients with multicystic kidney, renal agenesia and renal hypodysplasia, or underwent single nephrectomy. Materials and Methods This prospective, multicentric study was conducted in collaboration between the Pediatric Surgery Unit in Foggia and the Pediatric Nephrology Unit in Bari, Italy. We enrolled 80 children with CAKUT (40 hypodysplasia, 22 agenetic; 10 multicystic; 8 nephrectomy) who underwent extensive urological and nephrological workup. Exclusion criteria were recent urinary tract infections or pyelonephritis, age > 14 years, presence of systemic disease, or hypertension. A single urine sample was collected in a noninvasive way and processed for measuring by enzyme-linked immunosorbent assay urine levels of MCP-1, EGF, β2M, and FAS-L. As control, urine samples were taken from 30 healthy children. Furthermore, we evaluated the urinary ratios uEGF/uMCP-1 (indicator of regenerative vs inflammatory response) and uEGF/uβ2M (indicator of regenerative response vs. tubular damage). Results These results suggest that urinary levels of MCP-1 are overexpressed in CAKUT patients. Furthermore, our findings clearly demonstrated that both uEGF/uMCP-1 and uEGF/uβ2M ratios were significantly downregulated in all patient groups when compared with the control group. Conclusion These findings further support that CAKUT patients may, eventually, experience progressive renal damage and poor regenerative response. The increased urinary levels of MCP-1 in all groups of CAKUT patients suggested that the main factor responsible for the above effects is chronic renal inflammation mediated by local monocytes

    Quality of Life after Type A Aortic Dissection Surgery in the United Kingdom: The QUADS Study

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    \ua9 2025. The Author(s).Background Acute Type A aortic dissection (TAAD) is a life-threatening condition that carries significant mortality and morbidity; a proportion of the survivors might require further aortic procedures in the mid-/long-term follow-up. Quality of life (QoL) after TAAD is not well studied. Quality of life after Type A Aortic Dissection Surgery (QUADS) is the first multicentre study to assess QoL in survivors of surgically treated TAAD. Methods A tailored questionnaire for survivors of TAAD was designed with patient and public involvement. Patients who underwent surgery from 2018 to 2022 in eight United Kingdom centres were invited to participate. Preoperative, intraoperative, and postoperative prospectively collected data were collated and analyzed retrospectively. The data were analyzed with SPSS v29. Patient\u27s questionnaire was validated with a Cronbach\u27s alpha analysis, exploratory factor analysis, and AMOS confirmatory factor analysis. Three groups were created according to QoL (Good, Fair, Poor). Results A total of 162 patients were recruited. Majority were male with a mean age of 63 years (24-92). Surgical procedures for TAAD were root and ascending aorta replacement (n = 61, 38%), ascending (n = 81, 50%), and/or arch replacement (n = 20, 12%). Eleven patients (7%) required later intervention. Patient\u27s answers regarding overall QoL were good (n = 67, 41%), fair (n = 89, 55%), and poor (n = 6, 4%). Neurological complications, circulatory arrest duration, reoperation for bleeding, postoperative myocardial infraction, arrhythmias, wound infection, and patient destination at discharge have been identified as main variables impacting on QoL after TAAD surgery across different domains of this questionnaire. Conclusion QUADS questionnaire is the first tailored and validated questionnaire for TAAD survivors. Results in the United Kingdom population suggest that it is a useful tool to assess QoL after TAAD surgery

    Surgical aortic valve replacement in the era of transcatheter aortic valve implantation: a review of the UK national database

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    Objectives To date the reported outcomes of surgical aortic valve replacement (SAVR) are mainly in the settings of trials comparing it with evolving transcatheter aortic valve implantation. We set out to examine characteristics and outcomes in people who underwent SAVR reflecting a national cohort and therefore ‘real-world’ practice. Design Retrospective analysis of prospectively collected data of consecutive people who underwent SAVR with or without coronary artery bypass graft (CABG) surgery between April 2013 and March 2018 in the UK. This included elective, urgent and emergency operations. Participants’ demographics, preoperative risk factors, operative data, in-hospital mortality, postoperative complications and effect of the addition of CABG to SAVR were analysed. Setting 27 (90%) tertiary cardiac surgical centres in the UK submitted their data for analysis. Participants 31 277 people with AVR were identified. 19 670 (62.9%) had only SAVR and 11 607 (37.1%) had AVR+CABG. Results In-hospital mortality for isolated SAVR was 1.9% (95% CI 1.6% to 2.1%) and was 2.4% for AVR+CABG. Mortality by age category for SAVR only were: 75 years=2.2%. For SAVR+CABG these were; 2.2%, 1.8% and 3.1%. For different categories of EuroSCORE, mortality for SAVR in low risk people was 1.3%, in intermediate risk 1% and for high risk 3.9%. 74.3% of the operations were elective, 24% urgent and 1.7% emergency/salvage. The incidences of resternotomy for bleeding and stroke were 3.9% and 1.1%, respectively. Multivariable analyses provided no evidence that concomitant CABG influenced outcome. However, urgency of the operation, poor ventricular function, higher EuroSCORE and longer cross clamp and cardiopulmonary bypass times adversely affected outcomes. Conclusions Surgical SAVR±CABG has low mortality risk and a low level of complications in the UK in people of all ages and risk factors. These results should inform consideration of treatment options in people with aortic valve disease

    Surgical aortic valve replacement in the era of transcatheter aortic valve implantation: a review of the UK national database

    Get PDF
    Objectives To date the reported outcomes of surgical aortic valve replacement (SAVR) are mainly in the settings of trials comparing it with evolving transcatheter aortic valve implantation. We set out to examine characteristics and outcomes in people who underwent SAVR reflecting a national cohort and therefore ‘real-world’ practice. Design Retrospective analysis of prospectively collected data of consecutive people who underwent SAVR with or without coronary artery bypass graft (CABG) surgery between April 2013 and March 2018 in the UK. This included elective, urgent and emergency operations. Participants’ demographics, preoperative risk factors, operative data, in-hospital mortality, postoperative complications and effect of the addition of CABG to SAVR were analysed. Setting 27 (90%) tertiary cardiac surgical centres in the UK submitted their data for analysis. Participants 31 277 people with AVR were identified. 19 670 (62.9%) had only SAVR and 11 607 (37.1%) had AVR+CABG. Results In-hospital mortality for isolated SAVR was 1.9% (95% CI 1.6% to 2.1%) and was 2.4% for AVR+CABG. Mortality by age category for SAVR only were: 75 years=2.2%. For SAVR+CABG these were; 2.2%, 1.8% and 3.1%. For different categories of EuroSCORE, mortality for SAVR in low risk people was 1.3%, in intermediate risk 1% and for high risk 3.9%. 74.3% of the operations were elective, 24% urgent and 1.7% emergency/salvage. The incidences of resternotomy for bleeding and stroke were 3.9% and 1.1%, respectively. Multivariable analyses provided no evidence that concomitant CABG influenced outcome. However, urgency of the operation, poor ventricular function, higher EuroSCORE and longer cross clamp and cardiopulmonary bypass times adversely affected outcomes. Conclusions Surgical SAVR±CABG has low mortality risk and a low level of complications in the UK in people of all ages and risk factors. These results should inform consideration of treatment options in people with aortic valve disease

    Validating AU Microscopii d with Transit Timing Variations

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    AU Mic is a young (22 Myr) nearby exoplanetary system that exhibits excess TTVs that cannot be accounted for by the two known transiting planets nor stellar activity. We present the statistical "validation" of the tentative planet AU Mic d (even though there are examples of "confirmed" planets with ambiguous orbital periods). We add 18 new transits and nine midpoint times in an updated TTV analysis to prior work. We perform the joint modeling of transit light curves using EXOFASTv2 and extract the transit midpoint times. Next, we construct an O-C diagram and use Exo-Striker to model the TTVs. We generate TTV log-likelihood periodograms to explore possible solutions for the period of planet d and then follow those up with detailed TTV and RV MCMC modeling and stability tests. We find several candidate periods for AU Mic d, all of which are near resonances with AU Mic b and c of varying order. Based on our model comparisons, the most-favored orbital period of AU Mic d is 12.73596+/-0.00793 days (T_{C,d}=2458340.55781+/-0.11641 BJD), which puts the three planets near a 4:6:9 mean-motion orbital resonance. The mass for d is 1.053+/-0.511 M_E, making this planet Earth-like in mass. If confirmed, AU Mic d would be the first known Earth-mass planet orbiting a young star and would provide a valuable opportunity in probing a young terrestrial planet's atmosphere. Additional TTV observation of the AU Mic system are needed to further constrain the planetary masses, search for possible transits of AU Mic d, and detect possible additional planets beyond AU Mic c.Comment: 89 pages, 35 figures, 34 tables. Redid EXOFASTv2 transit modeling to recover more reasonable stellar posteriors, so redid Exo-Striker TTV modeling for consistency. Despite these changes, the overall results remain unchanged: the 12-7-day case is still the most favored. Submitted to AAS Journals on 2023 Feb 9t
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