Born-Infeld Theory and Stringy Causality

Fluctuations around a non-trivial solution of Born-Infeld theory have a limiting speed given not by the Einstein metric but the Boillat metric. The Boillat metric is S-duality invariant and conformal to the open string metric. It also governs the propagation of scalars and spinors in Born-Infeld theory. We discuss the potential clash between causality determined by the closed string and open string light cones and find that the latter never lie outside the former. Both cones touch along the principal null directions of the background Born-Infeld field. We consider black hole solutions in situations in which the distinction between bulk and brane is not sharp such as space filling branes and find that the location of the event horizon and the thermodynamic properties do not depend on whether one uses the closed or open string metric. Analogous statements hold in the more general context of non-linear electrodynamics or effective quantum-corrected metrics. We show how Born-Infeld action to second order might be obtained from higher-curvature gravity in Kaluza-Klein theory. Finally we point out some intriguing analogies with Einstein-Schr\"odinger theory.Comment: 31 pages, 4 figures, LaTex; Some comments and references adde

Nearly Complete Genome Sequence of a Novel Phlebovirus-Like Virus Detected in a Human Plasma Sample by High-Throughput Sequencing.

Here, we report a novel phlebovirus-like virus sequence detected in a plasma sample from a febrile adult patient collected in the United Republic of Tanzania in 2014. A nearly complete RNA sequence was generated by high-throughput sequencing on a HiSeq 2500 instrument and further confirmed after repeating the analysis, starting from the initial sample

COVID-19 risk stratification algorithms based on sTREM-1 and IL-6 in emergency department.

The coronavirus disease 2019 (COVID-19) pandemic has led to surges of patients presenting to emergency departments (EDs) and potentially overwhelming health systems. We sought to assess the predictive accuracy of host biomarkers at clinical presentation to the ED for adverse outcome. Prospective observational study of PCR-confirmed COVID-19 patients in the ED of a Swiss hospital. Concentrations of inflammatory and endothelial dysfunction biomarkers were determined at clinical presentation. We evaluated the accuracy of clinical signs and these biomarkers in predicting 30-day intubation/mortality, and oxygen requirement by calculating the area under the receiver-operating characteristic curve and by classification and regression tree analysis. Of 76 included patients with COVID-19, 24 were outpatients or hospitalized without oxygen requirement, 35 hospitalized with oxygen requirement, and 17 intubated/died. We found that soluble triggering receptor expressed on myeloid cells had the best prognostic accuracy for 30-day intubation/mortality (area under the receiver-operating characteristic curve, 0.86; 95% CI, 0.77-0.95) and IL-6 measured at presentation to the ED had the best accuracy for 30-day oxygen requirement (area under the receiver-operating characteristic curve, 0.84; 95% CI, 0.74-0.94). An algorithm based on respiratory rate and sTREM-1 predicted 30-day intubation/mortality with 94% sensitivity and 0.1 negative likelihood ratio. An IL-6-based algorithm had 98% sensitivity and 0.04 negative likelihood ratio for 30-day oxygen requirement. sTREM-1 and IL-6 concentrations in COVID-19 in the ED have good predictive accuracy for intubation/mortality and oxygen requirement. sTREM-1- and IL-6-based algorithms are highly sensitive to identify patients with adverse outcome and could serve as early triage tools

3-D simulation of water and heat transport processes in fuel cells during evaporative cooling and humidification

Evaporative cooling is a promising concept improve the efficiency and reduced costs of polymer electrolyte fuel cells (PEFCs) using modified gas diffusion layers with hydrophilic and hydrophobic lines. This concept has been demonstrated to simultaneously achieve cooling and membrane humidification in experiments. We have developed a 3-D numerical model of such an evaporative cooling cell to address remain questions from the experiments

Adequate plasma drug concentrations suggest that amoxicillin can be administered by continuous infusion using elastomeric pumps.

Elastomeric pumps can be useful for the administration of antibiotics in the outpatient setting. To determine amoxicillin degradation in elastomeric pumps, as well as the effectiveness of amoxicillin treatment administered by elastomeric pumps. Antibiotic degradation was measured in elastomeric pumps filled with 6 g of amoxicillin in 240 mL of NaCl 0.9% by drawing samples at 12 h intervals when stored in the fridge for 48 h and when worn around the waist for 24 h. Subsequently nine patients were treated with continuous infusions of 8 or 12 g of amoxicillin per day. Plasma amoxicillin concentrations were measured on each visit to the outpatient parenteral antibiotic therapy unit. Clinical outcome was verified 3 months after the end of treatment. Amoxicillin degradation in elastomeric pumps reached 10% after 48 h in the fridge and an additional 30% when worn around the waist for 24 h. Mean plasma drug concentrations achieved with 12 g of amoxicillin per day were 18.5 mg/L (95% CI 13.5-23.5), which is largely above the MIC of amoxicillin-susceptible bacteria. Nine patients treated for various complicated infections were cured and had no unexpected adverse effects. Adequate plasma drug concentrations and favourable clinical outcomes suggest that amoxicillin can be administered by continuous infusion using elastomeric pumps. This treatment modality does not fulfil formal requirements regarding pharmaceutical stability, but the resulting safety impact in patients is probably limited. Therapeutic drug monitoring and a close clinical follow-up are recommended if this route of administration is chosen

Pulse Oximetry as an Aid to Rule Out Pneumonia among Patients with a Lower Respiratory Tract Infection in Primary Care.

Guidelines recommend chest X-rays (CXRs) to diagnose pneumonia and guide antibiotic treatment. This study aimed to identify clinical predictors of pneumonia that are visible on a chest X-ray (CXR+) which could support ruling out pneumonia and avoiding unnecessary CXRs, including oxygen saturation. A secondary analysis was performed in a clinical trial that included patients with suspected pneumonia in Swiss primary care. CXRs were reviewed by two radiologists. We evaluated the association between clinical signs (heart rate > 100/min, respiratory rate ≥ 24/min, temperature ≥ 37.8 °C, abnormal auscultation, and oxygen saturation < 95%) and CXR+ using multivariate analysis. We also calculated the diagnostic performance of the associated clinical signs combined in a clinical decision rule (CDR), as well as a CDR derived from a large meta-analysis (at least one of the following: heart rate > 100/min, respiratory rate ≥ 24/min, temperature ≥ 37.8 °C, or abnormal auscultation). Out of 469 patients from the initial trial, 107 had a CXR and were included in this study. Of these, 26 (24%) had a CXR+. We found that temperature and oxygen saturation were associated with CXR+. A CDR based on the presence of either temperature ≥ 37.8 °C and/or an oxygen saturation level < 95% had a sensitivity of 69% and a negative likelihood ratio (LR-) of 0.45. The CDR from the meta-analysis had a sensitivity of 92% and an LR- of 0.37. The addition of saturation < 95% to this CDR increased the sensitivity (96%) and decreased the LR- (0.21). In conclusion, this study suggests that pulse oximetry could be added to a simple CDR to decrease the probability of pneumonia to an acceptable level and avoid unnecessary CXRs

Intracellular Zinc Activates KCNQ Channels by Reducing their Dependence on Phosphatidylinositol 4,5-bisphosphate

M-type (Kv7, KCNQ) potassium channels are proteins that control the excitability of neurons and muscle cells. Many physiological and pathological mechanisms of excitation operate via the suppression of M channel activity or expression. Conversely, pharmacological augmentation of M channel activity is a recognized strategy for the treatment of hyperexcitability disorders such as pain and epilepsy. However, physiological mechanisms resulting in M channel potentiation are rare. Here we report that intracellular free zinc directly and reversibly augments the activity of recombinant and native M channels. This effect is mechanistically distinct from the known redox-dependent KCNQ channel potentiation. Interestingly, the effect of zinc cannot be attributed to a single histidine- or cysteine-containing zinc-binding site within KCNQ channels. Instead, zinc dramatically reduces KCNQ channel dependence on its obligatory physiological activator, phosphatidylinositol 4,5-bisphosphate (PIP2). We hypothesize that zinc facilitates interactions of the lipid-facing interface of a KCNQ protein with the inner leaflet of the plasma membrane in a way similar to that promoted by PIP2. Because zinc is increasingly recognized as a ubiquitous intracellular second messenger, this discovery might represent a hitherto unknown native pathway of M channel modulation and provide a fresh strategy for the design of M channel activators for therapeutic purposes

Retrospective study on the usefulness of pulse oximetry for the identification of young children with severe illnesses and severe pneumonia in a rural outpatient clinic of Papua New Guinea.

This secondary analysis of data of a randomized controlled trial (RCT) retrospectively investigated the performance of pulse oximetry in identifying children with severe illnesses, with and without respiratory signs/symptoms, in a cohort of children followed for morbid episodes in an intervention trial assessing the efficacy of Intermittent Preventive Treatment for malaria in infants (IPTi) in Papua New Guinea (PNG) from June 2006 to May 2010. The IPTi study was conducted in a paediatric population visiting two health centres on the north coast of PNG in the Mugil area of the Sumkar District. A total of 669 children visited the clinic and a total of 1921 illness episodes were recorded. Inclusion criteria were: age between 3 and 27 months, full clinical record (signs/symptoms) and pulse oximetry used systematically to assess sick children at all visits. Children were excluded if they visited the clinic in the previous 14 days. The outcome measures were severe illness, severe pneumonia, pneumonia, defined by the Integrated Management of Childhood Illness (IMCI) definitions, and hospitalization. Out of 1921 illness episodes, 1663 fulfilled the inclusion criteria. A total of 139 severe illnesses were identified, of which 93 were severe pneumonia. The ROC curves of pulse oximetry (continuous variable) showed an AUC of 0.63, 0.68 and 0.65 for prediction of severe illness, severe pneumonia and hospitalization, respectively. Pulse oximetry allowed better discrimination between severe and non-severe illness, severe and non-severe pneumonia, admitted and non-admitted patients, in children ≤12-months of age relative to older patients. For the threshold of peripheral arterial oxygen saturation ≤ 94% measured by pulse oximetry (SpO2), unadjusted odds ratios for severe illness, severe pneumonia and hospitalization were 6.1 (95% Confidence Interval (CI) 3.9-9.8), 8.5 (4.9-14.6) and 5.9 (3.4-10.3), respectively. Pulse oximetry was helpful in identifying children with severe illness in outpatient facilities in PNG. A SpO2 of 94% seems the most discriminative threshold. Considering its affordability and ease of use, pulse oximetry could be a valuable additional tool assisting the decision to admit for treatment