319 research outputs found
Compton Scattering from the Deuteron and Extracted Neutron Polarizabilities
Differential cross sections for Compton scattering from the deuteron were
measured at MAX-lab for incident photon energies of 55 MeV and 66 MeV at
nominal laboratory angles of , , and . Tagged
photons were scattered from liquid deuterium and detected in three NaI
spectrometers. By comparing the data with theoretical calculations in the
framework of a one-boson-exchange potential model, the sum and difference of
the isospin-averaged nucleon polarizabilities, and (in units of fm),
have been determined. By combining the latter with the global-averaged value
for and using the predictions of the Baldin sum rule for
the sum of the nucleon polarizabilities, we have obtained values for the
neutron electric and magnetic polarizabilities of (total) (model) and (total) (model), respectively.Comment: 4 pages, 2 figures, revtex. The text is substantially revised. The
cross sections are slightly different due to improvements in the analysi
Transport and magnetic properties of NdCuGe compound
Electrical resistivity,heat capacity, and dc magnetization measurements were performed on the AlB2-type intermetallics NdCuGe and LaCuGe over the temperature range of 2–300K. NdCuGe exhibits magnetization attributable to Nd3+ moments, with an antiferromagnetic (AF) transition at 3.1K. Magnetization, heat capacity, and resistivitymeasurements were used to determine the crystalline electric field (CEF) splitting of the Nd3+ magnetic sublevels. The ground state is a doublet composed of ±5∕2 levels and the AF state is built from this magnetic doublet, with a reduction in the average sublattice magnetization attributable to site disorder among Cu–Ge sites. Low-temperature electrical transport is dominated by spin-disorder scattering among CEF-split levels and a small T2 spin fluctuation term. The latter is nearly two orders of magnitude smaller than previously observed in isostructural CeCuGe, for which the anomalous observed thermopower exponent was attributed to extended spin fluctuations above the magnetic transition. By contrast, simple-metallic behavior provides a good fit to the NdCuGe thermopower, thus, the CeCuGe results can be attributed to resonant scattering due to partial hybridization of the localized orbitals
Human H5N1 influenza infections in Cambodia 2005-2011: case series and cost-of-illness.
BACKGROUND: Southeast Asia has been identified as a potential epicentre of emerging diseases with pandemic capacity, including highly pathogenic influenza. Cambodia in particular has the potential for high rates of avoidable deaths from pandemic influenza due to large gaps in health system resources. This study seeks to better understand the course and cost-of-illness for cases of highly pathogenic avian influenza in Cambodia. METHODS: We studied the 18 laboratory-confirmed cases of avian influenza subtype H5N1 identified in Cambodia between January 2005 and August 2011. Medical records for all patients were reviewed to extract information on patient characteristics, travel to hospital, time to admission, diagnostic testing, treatment and disease outcomes. Further data related to costs was collected through interviews with key informants at district and provincial hospitals, the Ministry of Health and non-governmental organisations. An ingredient-based approach was used to estimate the total economic cost for each study patient. Costing was conducted from a societal perspective and included both financial and opportunity costs to the patient or carer. Sensitivity analysis was undertaken to evaluate potential change or variation in the cost-of-illness. RESULTS: Of the 18 patients studied, 11 (61%) were under the age of 18 years. The majority of patients (16, 89%) died, eight (44%) within 24 hours of hospital admission. There was an average delay of seven days between symptom onset and hospitalisation with patients travelling an average of 148 kilometres (8-476 km) to the admitting hospital. Five patients were treated with oseltamivir of whom two received the recommended dose. For the 16 patients who received all their treatment in Cambodia the average per patient cost of H5N1 influenza illness was US45 per patient (15.0%) of total economic cost. CONCLUSION: Cases of avian influenza in Cambodia were characterised by delays in hospitalisation, deficiencies in some aspects of treatment and a high fatality rate. The costs associated with medical care, particularly diagnostic testing and pharmaceutical therapy, were major contributors to the relatively high cost-of-illness
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Fractal Dimension Analysis of Transient Visual Evoked Potentials: Optimisation and Applications
Purpose
The visual evoked potential (VEP) provides a time series signal response to an external visual stimulus at the location of the visual cortex. The major VEP signal components, peak latency and amplitude, may be affected by disease processes. Additionally, the VEP contains fine detailed and non-periodic structure, of presently unclear relevance to normal function, which may be quantified using the fractal dimension. The purpose of this study is to provide a systematic investigation of the key parameters in the measurement of the fractal dimension of VEPs, to develop an optimal analysis protocol for application.
Methods
VEP time series were mathematically transformed using delay time, τ, and embedding dimension, m, parameters. The fractal dimension of the transformed data was obtained from a scaling analysis based on straight line fits to the numbers of pairs of points with separation less than r versus log(r) in the transformed space. Optimal τ, m, and scaling analysis were obtained by comparing the consistency of results using different sampling frequencies. The optimised method was then piloted on samples of normal and abnormal VEPs.
Results
Consistent fractal dimension estimates were obtained using τ = 4 ms, designating the fractal dimension = D2 of the time series based on embedding dimension m = 7 (for 3606 Hz and 5000 Hz), m = 6 (for 1803 Hz) and m = 5 (for 1000Hz), and estimating D2 for each embedding dimension as the steepest slope of the linear scaling region in the plot of log(C(r)) vs log(r) provided the scaling region occurred within the middle third of the plot. Piloting revealed that fractal dimensions were higher from the sampled abnormal than normal achromatic VEPs in adults (p = 0.02). Variances of fractal dimension were higher from the abnormal than normal chromatic VEPs in children (p = 0.01).
Conclusions
A useful analysis protocol to assess the fractal dimension of transformed VEPs has been developed
A Comparison of Clinical and Epidemiological Characteristics of Fatal Human Infections with H5N1 and Human Influenza Viruses in Thailand, 2004–2006
BACKGROUND: The National Avian Influenza Surveillance (NAIS) system detected human H5N1 cases in Thailand from 2004-2006. Using NAIS data, we identified risk factors for death among H5N1 cases and described differences between H5N1 and human (seasonal) influenza cases. METHODS AND FINDINGS: NAIS identified 11,641 suspect H5N1 cases (e.g. persons with fever and respiratory symptoms or pneumonia, and exposure to sick or dead poultry). All suspect H5N1 cases were tested with polymerase chain reaction (PCR) assays for influenza A(H5N1) and human influenza viruses. NAIS detected 25 H5N1 and 2074 human influenza cases; 17 (68%) and 22 (1%) were fatal, respectively. We collected detailed information from medical records on all H5N1 cases, all fatal human influenza cases, and a sampled subset of 230 hospitalized non-fatal human influenza cases drawn from provinces with ≥1 H5N1 case or human influenza fatality. Fatal versus non-fatal H5N1 cases were more likely to present with low white blood cell (p = 0.05), lymphocyte (p<0.02), and platelet counts (p<0.01); have elevated liver enzymes (p = 0.05); and progress to circulatory (p<0.001) and respiratory failure (p<0.001). There were no differences in age, medical conditions, or antiviral treatment between fatal and non-fatal H5N1 cases. Compared to a sample of human influenza cases, all H5N1 cases had direct exposure to sick or dead birds (60% vs. 100%, p<0.05). Fatal H5N1 and fatal human influenza cases were similar clinically except that fatal H5N1 cases more commonly: had fever (p<0.001), vomiting (p<0.01), low white blood cell counts (p<0.01), received oseltamivir (71% vs. 23%, p<.001), but less often had ≥1 chronic medical conditions (p<0.001). CONCLUSIONS: In the absence of diagnostic testing during an influenza A(H5N1) epizootic, a few epidemiologic, clinical, and laboratory findings might provide clues to help target H5N1 control efforts. Severe human influenza and H5N1 cases were clinically similar, and both would benefit from early antiviral treatment
The presence of extracellular matrix degrading metalloproteinases during fetal development of the intervertebral disc
Matrix metalloproteinases (MMPs) regulate connective tissue architecture and cell migration through extracellular matrix (ECM) degradation and are associated with both physiological and pathological processes. Although they are known to play a role in skeletal development, little is known about the role of MMPs in intervertebral disc (IVD) development. Sixteen fetal human lumbar spine segments, obtained at autopsy, were compared with five normal, non-fetal L4–L5 IVDs. Intensity and/or localization of immunohistochemical staining for MMP-1, -2, -3 and -14 were evaluated by three independent observers. MMP-2 production and activation was quantified by gelatin zymography. MMP-1 and -14 were abundantly present in the nucleus pulposus (NP) and notochordal (NC) cells of the fetal IVDs. In non-fetal IVDs, MMP-1 and -14 staining was significantly less intense (p = 0.001 and p < 0.001, respectively). MMP-3 was found in almost the entire IVD with no significant difference from non-fetal IVDs. MMP-2 staining in the NC and NP cells of the fetal IVD was moderate, but weak in the non-fetal IVD. Gelatin zymography showed a negative correlation of age with MMP-2 activity (p < 0.001). MMP-14 immunostaining correlated positively with MMP-2 activity (p = 0.001). For the first time, the presence of MMP-1, -2, -3 and -14 in the fetal human IVD is shown and the high levels of MMP-1, -2 and -14 suggest a role in the development of the IVD. In particular, the gradual decrease in MMP-2 activation during gestation pinpoints this enzyme as key player in fetal development, possibly through activation by MMP-1 and -14
Therapeutic Dosing of Acenocoumarol: Proposal of a Population Specific Pharmacogenetic Dosing Algorithm and Its Validation in North Indians
Objectives: To develop a population specific pharmacogenetic acenocoumarol dosing algorithm for north Indian patients and show its efficiency in dosage prediction. Methods: Multiple and linear stepwise regression analyses were used to include age, sex, height, weight, body surface area, smoking status, VKORC1-1639 G.A, CYP4F2 1347 G.A, CYP2C9*2,*3 and GGCX 12970 C.G polymorphisms as variables to generate dosing algorithms. The new dosing models were compared with already reported algorithms and also with the clinical data for various performance measures. Odds ratios for association of genotypes with drug sensitive and resistant groups were calculated. Results: The pharmacogenetic dosing algorithm generated by multiple regression analysis explains 41.4 % (p-value,0.001) of dosage variation. Validation of the new algorithm showed its predictive ability to be better than the already established algorithms based on similar variables. Its validity in our population is reflected by increased sensitivity, specificity, accuracy and decreased rates of over- and under- estimation in comparison to clinical data. The VKORC1-1639 G.A polymorphism was found to be strongly associated with acenocoumarol sensitivity according to recessive model. Conclusions: We have proposed an efficient north India specific pharmacogenetic acenocoumarol dosing algorithm whic
Homocysteine and other markers of cardiovascular risk during a manic episode in patients with bipolar disorder
Objective: To evaluate serum levels of different biomarkers associated with cardiovascular disease in patients with bipolar disorder (BD). Patients were prospectively evaluated in two separate instances: during acute mania and after remission of manic symptoms. All measurements were compared with those of healthy controls. Methods: The study included 30 patients with BD and 30 healthy controls, matched for gender and age. Biochemical parameters evaluated included homocysteine (Hcy), folic acid, vitamin B12, ferritin, creatine kinase (CK) and C-reactive protein (CRP). Results: Hcy levels were significantly higher in the BD patients, both during mania and after achieving euthymia. When Hcy was adjusted for body mass index, there was no significant difference between patients and controls. Ferritin was the only marker that showed a significant decrease during mania when compared to both euthymic patients and controls. There were no significant differences for folate, vitamin B12, CK and CRP. Conclusions: These findings do not show an association between alterations of markers of cardiovascular risk during manic episodes. Further studies are necessary to determine factors and mechanisms associated with cardiovascular risk in patients with BD
Prevalence and molecular characterization of Glucose-6-Phosphate dehydrogenase deficient variants among the Kurdish population of Northern Iraq
<p>Abstract</p> <p>Background</p> <p>Glucose-6-Phosphate dehydrogenase (G6PD) is a key enzyme of the pentose monophosphate pathway, and its deficiency is the most common inherited enzymopathy worldwide. G6PD deficiency is common among Iraqis, including those of the Kurdish ethnic group, however no study of significance has ever addressed the molecular basis of this disorder in this population. The aim of this study is to determine the prevalence of this enzymopathy and its molecular basis among Iraqi Kurds.</p> <p>Methods</p> <p>A total of 580 healthy male Kurdish Iraqis randomly selected from a main regional premarital screening center in Northern Iraq were screened for G6PD deficiency using methemoglobin reduction test. The results were confirmed by quantitative enzyme assay for the cases that showed G6PD deficiency. DNA analysis was performed on 115 G6PD deficient subjects, 50 from the premarital screening group and 65 unrelated Kurdish male patients with documented acute hemolytic episodes due to G6PD deficiency. Analysis was performed using polymerase chain reaction/restriction fragment length polymorphism for five deficient molecular variants, namely G6PD Mediterranean (563 C→T), G6PD Chatham (1003 G→A), G6PD A- (202 G→A), G6PD Aures (143 T→C) and G6PD Cosenza (1376 G→C), as well as the silent 1311 (C→T) mutation.</p> <p>Results</p> <p>Among 580 random Iraqi male Kurds, 63 (10.9%) had documented G6PD deficiency. Molecular studies performed on a total of 115 G6PD deficient males revealed that 101 (87.8%) had the G6PD Mediterranean variant and 10 (8.7%) had the G6PD Chatham variant. No cases of G6PD A-, G6PD Aures or G6PD Cosenza were identified, leaving 4 cases (3.5%) uncharacterized. Further molecular screening revealed that the silent mutation 1311 was present in 93/95 of the Mediterranean and 1/10 of the Chatham cases.</p> <p>Conclusions</p> <p>The current study revealed a high prevalence of G6PD deficiency among Iraqi Kurdish population of Northern Iraq with most cases being due to the G6PD Mediterranean and Chatham variants. These results are similar to those reported from neighboring Iran and Turkey and to lesser extent other Mediterranean countries.</p
Machine learning prediction models in orthopedic surgery: A systematic review in transparent reporting
Machine learning (ML) studies are becoming increasingly popular in orthopedics but lack a critically appraisal of their adherence to peer-reviewed guidelines. The objective of this review was to (1) evaluate quality and transparent reporting of ML prediction models in orthopedic surgery based on the transparent reporting of multivariable prediction models for individual prognosis or diagnosis (TRIPOD), and (2) assess risk of bias with the Prediction model Risk Of Bias ASsessment Tool. A systematic review was performed to identify all ML prediction studies published in orthopedic surgery through June 18th, 2020. After screening 7138 studies, 59 studies met the study criteria and were included. Two reviewers independently extracted data and discrepancies were resolved by discussion with at least two additional reviewers present. Across all studies, the overall median completeness for the TRIPOD checklist was 53% (interquartile range 47%-60%). The overall risk of bias was low in 44% (n = 26), high in 41% (n = 24), and unclear in 15% (n = 9). High overall risk of bias was driven by incomplete reporting of performance measures, inadequate handling of missing data, and use of small datasets with inadequate outcome numbers. Although the number of ML studies in orthopedic surgery is increasing rapidly, over 40% of the existing models are at high risk of bias. Furthermore, over half incompletely reported their methods and/or performance measures. Until these issues are adequately addressed to give patients and providers trust in ML models, a considerable gap remains between the development of ML prediction models and their implementation in orthopedic practice
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