3,422 research outputs found

    Regions of significant influence on unforced global mean surface air temperature variability in climate models

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    We document the geographic regions where local variability is most associated with unforced global mean surface air temperature (GMT) variability in Coupled Model Intercomparison Project Phase 5 coupled global climate models (GCMs) at both the subdecadal and interdecadal timescales. For this purpose, Regions of Significant Influence on GMT are defined as locations that have a statistically significant correlation between local surface air temperature (SAT) and GMT (with a regression slope greater than 1), and where local SAT variation leads GMT variation in time. In both GCMs and observations, subdecadal timescale GMT variability is most associated with SAT variation over the eastern equatorial Pacific. At the interdecadal timescale, GMT variability is also linked with SAT variation over the Pacific in many GCMs, but the particular spatial patterns are GCM dependent, and several GCMs indicate a primary association between GMT and SAT over the Southern Ocean. We find that it is difficult to validate GCM behavior at the interdecadal timescale because the pattern derived from observations is highly depended on the method used to remove the forced variability from the record. The magnitude of observed GMT variability is near the ensemble median at the subdecadal timescale but well above the median at the interdecadal timescale. GCMs with a stronger subdecadal relationship between GMT and SAT over the Pacific tend to have more variable subdecadal GMT while GCMs with a stronger interdecadal relationship between GMT and SAT over parts of the Southern Ocean tend to have more variable GMT

    What colour is penguin guano?

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    The identification and quantification of Antarctic Pygoscelis penguin colonies depends increasingly on recognition of the characteristic optical properties of guano deposits, but almost all knowledge of these properties until now has been compromised by resolution and atmospheric propagation effects. Here we present hyperspectral reflectance data in the range 350–2500 nm, collected in situ from fresh guano deposits in Pygoscelis penguin colonies on Signy Island, South Orkney Islands. The period of data collection included the transition from predominantly white guano to the pink coloration characteristic of a krill-rich diet. The main identifiable features in the spectra are a broad absorption feature centred around 550 nm, responsible for the pink coloration and identified with the pigment astaxanthin, as well as several water absorption features. Variations in these features are responsible for differentiation between spectra. From these results we propose two spectral indices suitable for use with satellite data, one of which responds to the presence of astaxanthin in the guano and the other to water. Our results do not allow us to differentiate between penguin species from their guano, but do suggest that the breeding phenology of Pygoscelis penguins could be determined from a time series of multispectral imagery.The fieldwork necessary for this work was supported by BAS through a Collaborative Gearing Scheme award CGS-97 to W.G. Rees and P.N. Trathan, and the ASD FieldSpec Pro was made available through an award (ref. 696.0614) from the UK NERC Field Spectroscopy Facility. We acknowledge with gratitude the support and companionship of the entire staff of the BAS research station at Signy, and especially of M. Jobson, the Base Commander. J.A. Brown is supported by a NERC PhD studentship NE/L501633/1

    Radiation Retinopathy: Case report and review

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    BACKGROUND: Ocular damage from radiation treatment is a well established phenomenon. Many factors are now known to influence the incidence of radiation retinopathy, including total dosage and daily fraction size. Patients who are diabetic, hypertensive or received previous chemotherapy are more susceptible to radiation retinopathy. CASE PRESENTATION: A 55 year old male was referred from the oncology department with epiphora. His medical history included Type 2 Insulin treated Diabetes Mellitus and hypertension. One year prior to presentation he had undergone a total rhinectomy with a 4 week course of post-operative radiotherapy for an aggressive sqaumous cell carcinoma of the nose. On examination the visual acuity was noted to be 6/36 left eye and 6/9 right eye. Posterior segment examination revealed marked retinal ischaemia present in the posterior pole and macular region of both eyes. The appearance was not thought to be typical of diabetic changes, radiation retinopathy being the more likely diagnosis especially in view of his history. Over the next four months the vision in both eyes rapidly deteriorated to 3/60 left eye and 1/60 right eye. Bilateral pan retinal photocoagulation was thought to be appropriate treatment at this point. CONCLUSION: This case highlights the importance for ophthalmologists and oncologists to be aware of the close relationship between diabetes and radiation treatment and the profound rapid impact this combination of factors may have on visual function. Radiation is being used with increasing frequency for ocular and orbital disease, because of this more cases of radiation retinopathy may become prevalent. Factors which may potentiate radiation retinopathy should be well known including, increased radiation dosage, increased fraction size, concomitant systemic vascular disease and use of chemotherapy. Counselling should be offered in all cases at risk of visual loss. As no effective treatment currently exists to restore visual function, monitoring of visual acuity in all cases and early referral to the ophthalmologist as appropriate is warranted

    Relationship between gene co-expression and probe localization on microarray slides

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    BACKGROUND: Microarray technology allows simultaneous measurement of thousands of genes in a single experiment. This is a potentially useful tool for evaluating co-expression of genes and extraction of useful functional and chromosomal structural information about genes. RESULTS: In this work we studied the association between the co-expression of genes, their location on the chromosome and their location on the microarray slides by analyzing a number of eukaryotic expression datasets, derived from the S. cerevisiae, C. elegans, and D. melanogaster. We find that in several different yeast microarray experiments the distribution of the number of gene pairs with correlated expression profiles as a function of chromosomal spacing is peaked at short separations and has two superimposed periodicities. The longer periodicity has a spacing of 22 genes (~42 Kb), and the shorter periodicity is 2 genes (~4 Kb). CONCLUSION: The relative positioning of DNA probes on microarray slides and source plates introduces subtle but significant correlations between pairs of genes. Careful consideration of this spatial artifact is important for analysis of microarray expression data. It is particularly relevant to recent microarray analyses that suggest that co-expressed genes cluster along chromosomes or are spaced by multiples of a fixed number of genes along the chromosome

    HIBCH mutations can cause Leigh-like disease with combined deficiency of multiple mitochondrial respiratory chain enzymes and pyruvate dehydrogenase

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    Background: Deficiency of 3-hydroxy-isobutyryl-CoA hydrolase (HIBCH) caused by HIBCH mutations is a rare cerebral organic aciduria caused by disturbance of valine catabolism. Multiple mitochondrial respiratory chain (RC) enzyme deficiencies can arise from a number of mechanisms, including defective maintenance or expression of mitochondrial DNA. Impaired biosynthesis of iron-sulphur clusters and lipoic acid can lead to pyruvate dehydrogenase complex (PDHc) deficiency in addition to multiple RC deficiencies, known as the multiple mitochondrial dysfunctions syndrome. Methods: Two brothers born to distantly related Pakistani parents presenting in early infancy with a progressive neurodegenerative disorder, associated with basal ganglia changes on brain magnetic resonance imaging, were investigated for suspected Leigh-like mitochondrial disease. The index case had deficiencies of multiple RC enzymes and PDHc in skeletal muscle and fibroblasts respectively, but these were normal in his younger brother. The observation of persistently elevated hydroxy-C4-carnitine levels in the younger brother led to suspicion of HIBCH deficiency, which was investigated by biochemical assay in cultured skin fibroblasts and molecular genetic analysis. Results: Specific spectrophotometric enzyme assay revealed HIBCH activity to be below detectable limits in cultured skin fibroblasts from both brothers. Direct Sanger sequence analysis demonstrated a novel homozygous pathogenic missense mutation c.950G <A; p.Gly317Glu in the HIBCH gene, which segregated with infantile-onset neurodegeneration within the family. Conclusions: HIBCH deficiency, a disorder of valine catabolism, is a novel cause of the multiple mitochondrial dysfunctions syndrome, and should be considered in the differential diagnosis of patients presenting with multiple RC deficiencies and/or pyruvate dehydrogenase deficiency

    From Classroom to Practice: Implementing the Core Set of Outcome Measures in a Student-Led Clinic

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    Background: Literature suggests that Clinical Practice Guidelines (CPGs) are insufficient for facilitating behavior change in clinicians. However, translating research to clinical practice is essential for evidence-based practice. Prior to publication of the Core Set of Outcome Measures (CSOMs) for Adults with Neurologic Conditions CPG, all recommended outcome measures (OMs) were included in the University of Puget Sound curriculum. Beginning Fall 2018, didactic instruction adjusted such that clinical decision-making for the CSOMs was instructed as outlined in the CPG. Purpose: To determine whether utilization of CSOMs in a student-led neurologic outpatient physical therapy clinic changed after students received intentional didactic instruction on CPG utilization. The secondary aim was to determine whether OM utilization frequency changed. Methods: Patient diagnosis, patient ambulatory status, and frequencies of OMs administered were collected for all patients who attended a student-led neurologic physical therapy clinic between 2017 and 2022. Descriptive and inferential statistical tests were conducted using non-parametric methods. Results: Utilization of the CSOMs increased by 41% overall and 59% for ambulatory patients. Prior to Fall 2018, the most frequently utilized OMs were the Timed Up and Go (TUG), 5 Times Sit to Stand (5xSTS), Dynamic Gait Index, and Four Square Step Test. Following publication and instruction of the CPG, the most frequently utilized OMs were the TUG, 5xSTS, Activities-Specific Balance Confidence Scale, and Functional Gait Assessment. The frequency of overall OM utilization did not change. Conclusion: Students increased utilization of CSOMs after intentional didactic instruction. Frequency of overall OM utilization remained unchanged

    Controlling Level of Unconsciousness by Titrating Propofol with Deep Reinforcement Learning

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    Reinforcement Learning (RL) can be used to fit a mapping from patient state to a medication regimen. Prior studies have used deterministic and value-based tabular learning to learn a propofol dose from an observed anesthetic state. Deep RL replaces the table with a deep neural network and has been used to learn medication regimens from registry databases. Here we perform the first application of deep RL to closed-loop control of anesthetic dosing in a simulated environment. We use the cross-entropy method to train a deep neural network to map an observed anesthetic state to a probability of infusing a fixed propofol dosage. During testing, we implement a deterministic policy that transforms the probability of infusion to a continuous infusion rate. The model is trained and tested on simulated pharmacokinetic/pharmacodynamic models with randomized parameters to ensure robustness to patient variability. The deep RL agent significantly outperformed a proportional-integral-derivative controller (median absolute performance error 1.7% +/- 0.6 and 3.4% +/- 1.2). Modeling continuous input variables instead of a table affords more robust pattern recognition and utilizes our prior domain knowledge. Deep RL learned a smooth policy with a natural interpretation to data scientists and anesthesia care providers alike.Comment: International Conference on Artificial Intelligence in Medicine 202

    Cervical length and quantitative fetal fibronectin in the prediction of spontaneous preterm birth in asymptomatic women with congenital uterine anomaly

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    BACKGROUND: Congenital uterine anomalies (CUA) are associated with late miscarriage and spontaneous preterm birth (sPTB). OBJECTIVES: Our aim was to 1) determine the rate of sPTB in each type of CUA and 2) assess the performance of quantitative fetal fibronectin (qfFN) and transvaginal cervical length (CL) measurement by ultrasound in asymptomatic women with CUA for the prediction of sPTB at <34 and <37 weeks of gestation. STUDY DESIGN: This was a retrospective cohort of women with CUA asymptomatic for sPTB, from four UK tertiary referral centres (2001-2016). CUAs were categorised into fusion (unicornuate, didelphic and bicornuate uteri) or resorption defects (septate, with or without resection and arcuate uteri), based on pre-pregnancy diagnosis. All women underwent serial transvaginal ultrasound CL assessment in the second trimester (16 to 24 weeks' gestation); a subgroup underwent qfFN testing from 18 weeks' gestation. We investigated the relationship between CUA and predictive test performance for sPTB before 34 and 37 weeks' gestation. RESULTS: Three hundred and nineteen women were identified as having CUA within our high-risk population. 7% (23/319) delivered spontaneously <34 weeks, and 18% (56/319) <37 weeks' gestation. Rates of sPTB by type were: 26% (7/27) for unicornuate, 21% (7/34) for didelphic, 16% (31/189) for bicornuate, 13% (7/56) for septate and 31% (4/13) for arcuate. 80% (45/56) of women who had sPTB <37 weeks did not develop a short CL (<25 mm) during the surveillance period (16-24 weeks). The diagnostic accuracy of short CL had low sensitivity (20.3) for predicting sPTB <34 weeks. Cervical Length had ROC AUC of 0.56 (95% CI 0.48 to 0.64) and 0.59 (95% CI 0.55 to 0.64) for prediction of sPTB <34 and 37 weeks' respectively. The AUC for CL to predict sPTB <34 weeks was 0.48 for fusion defects (95% CI 0.39 to 0.57) but 0.78 (95% CI 0.66 to 0.91) for women with resorption defects. Overall quantitative fetal fibronectin had a AUC of 0.63 (95% CI 0.49 to 0.77) and 0.58 (95% CI 0.49 to 0.68) for prediction of sPTB <34 and 37 weeks, respectively. AUC for prediction of sPTB <37 weeks with qfFN for fusion defects was 0.52 (95% CI 0.41 to 0.63), but 0.79 (0.63 to 0.95) for women with resorption defects. Results were similar when women with intervention were excluded. CONCLUSION: Commonly used markers CL and qfFN have utility in prediction of sPTB in resorption congenital uterine defects but not in fusion defects. This is contrary to other high-risk populations. These findings need to be accounted for when planning antenatal care and have potential implications for predictive tests used in sPTB surveillance and intervention

    Full Genome Characterization of the Culicoides-Borne Marsupial Orbiviruses: Wallal Virus, Mudjinbarry Virus and Warrego Viruses

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    Viruses belonging to the species Wallal virus and Warrego virus of the genus Orbivirus were identified as causative agents of blindness in marsupials in Australia during 1994/5. Recent comparisons of nucleotide (nt) and amino acid (aa) sequences have provided a basis for the grouping and classification of orbivirus isolates. However, full-genome sequence data are not available for representatives of all Orbivirus species. We report full-genome sequence data for three additional orbiviruses: Wallal virus (WALV); Mudjinabarry virus (MUDV) and Warrego virus (WARV). Comparisons of conserved polymerase (Pol), sub-core-shell 'T2' and core-surface 'T13' proteins show that these viruses group with other Culicoides borne orbiviruses, clustering with Eubenangee virus (EUBV), another orbivirus infecting marsupials. WARV shares <70% aa identity in all three conserved proteins (Pol, T2 and T13) with other orbiviruses, consistent with its classification within a distinct Orbivirus species. Although WALV and MUDV share <72.86%/67.93% aa/nt identity with other orbiviruses in Pol, T2 and T13, they share >99%/90% aa/nt identities with each other (consistent with membership of the same virus species - Wallal virus). However, WALV and MUDV share <68% aa identity in their larger outer capsid protein VP2(OC1), consistent with membership of different serotypes within the species - WALV-1 and WALV-2 respectively
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