Ultimate Intelligence Part I: Physical Completeness and Objectivity of Induction

We propose that Solomonoff induction is complete in the physical sense via several strong physical arguments. We also argue that Solomonoff induction is fully applicable to quantum mechanics. We show how to choose an objective reference machine for universal induction by defining a physical message complexity and physical message probability, and argue that this choice dissolves some well-known objections to universal induction. We also introduce many more variants of physical message complexity based on energy and action, and discuss the ramifications of our proposals.Comment: Under review at AGI-2015 conference. An early draft was submitted to ALT-2014. This paper is now being split into two papers, one philosophical, and one more technical. We intend that all installments of the paper series will be on the arxi

Current and emerging evidence for immunomodulatory therapy in community-acquired pneumonia

Community-acquired pneumonia (CAP) is the most common infectious disease related cause of death worldwide despite the use of effective antimicrobials. Much of the morbidity and mortality seen in CAP patients at high risk of death has been attributed to exaggerated host responses that result in bystander tissue damage and organ failure. Therefore there is great need to further understand the effect of hyperinflammatory phenotypes on CAP outcomes and develop adjuvant therapy that can attenuate excessive inflammatory responses without compromising host defense. Furthermore, there is growing concern regarding the development of antimicrobial resistance and recent research aims to modulate immune mechanisms that boost pathogen killing and clearance. In this review we summarize the growing body of evidence for the use of adjuvant immunomodulators in the treatment of CAP and highlight emerging immunomodulators that have been tested in pre-clinical studies, which need to be evaluated and developed for clinical trials. In summary, current evidence supports the use of macrolide combination antibiotic therapy and unless contraindicated continuation of pre-admission statin and antiplatelet therapy. Corticosteroids are beneficial in the context of septic shock and critical illness related adrenal insufficiency and may be of benefit to individuals with severe CAP and a hyperinflammatory phenotype given the potential for improving patient-centered and economic outcomes with negligible adverse effects. Despite much promise in pre-clinical work, many clinical trials of drugs targeting the coagulation pathways have unfortunately failed to demonstrate clinical benefits in humans. Results of trials evaluating aspirin, intravenous immunoglobulin (IVIg) and thrombomodulin are awaited and may yet influence practice, whilst further identification of inflammatory phenotypes will in the future allow personalized approaches and identify subgroups of patients that may respond to adjuvants that have previously not demonstrated favorable outcomes when used in heterogeneous cohorts

Constipation in children

Constipation in children is a universal problem, occurring in 0.7-28% of the population. The exact aetiology is unknown, but the majority of children have a functional, rather than organic, aetiology. Symptoms associated with constipation include abdominal pain, a poor appetite and faecal incontinence, all of which interfere with the quality of life of the child and his or her family. Early intervention with appropriate management is necessary to prevent ongoing sequelae. Once an organic cause has been excluded, a programme of intervention should be implemented, namely evacuation of any faecal mass present, followed by regular maintenance therapy to encourage evacuation of a daily soft stool for at least 2-3 months, prior to gradual withdrawal. Emotional support, exercise and dietary modification are linked to the therapy and will ensure a successful outcome. Failure to implement the protocol may result in ongoing problems in up to 50% of children as theyenter adulthood

Determining the relative sensitivity of benthic diatoms to atrazine using rapid toxicity testing: A novel method

Herbicides pose a potential threat to aquatic ecosystems, especially to phototrophic organisms such as benthic diatoms. Benthic diatoms may be a valuable indicator of the toxic impacts of herbicides in aquatic systems. However, this requires information on the herbicide sensitivity of a wide range of freshwater benthic diatom taxa. Unfortunately this information is only available for a limited number of species as current methods of developing new algae toxicity tests on individual taxa are lengthy and costly. To address this issue, we developed a new rapid toxicity test method to test natural benthic communities, from which the relative herbicide sensitivity of many individual taxa can be derived. This involved the collection of natural benthic communities from rocks in situ, which were placed directly into laboratory toxicity tests. Sensitivity data for several diatom genera in a 48hour exposure toxicity test were produced, without the need for cultures or multiple site visits. After exposure to the highest treatment of atrazine (500μgL-1) there were significant declines of healthy cells in the most sensitive genera: Gomphonema declined by 74%, Amphora by 62%, Cymbella by 54% and Ulnaria by 34% compared to control levels. In contrast, the genera, Eunotia, Achnanthidium and Navicula, had no statistically significant decline in cell health. This method can identify the diatom taxa most at risk of herbicide toxicity within the natural benthic diatom community. The rapid toxicity testing method presented is a simple and effective method to obtain sensitivity data for multiple taxa within a natural benthic diatom community in a relatively short period of time. © 2014 Elsevier B.V

Tropical belt width proportionately more sensitive to aerosols than greenhouse gases

The tropical belt has widened during the last several decades, and both internal variability and anthropogenic forcings have contributed. Although greenhouse gases and stratospheric ozone depletion have been implicated as primary anthropogenic drivers of tropical expansion, the possible role of other drivers remains uncertain. Here, we analyze the tropical belt width response to idealized perturbations in multiple models. Our results show that absorbing black carbon (BC) aerosol drives tropical expansion, and scattering sulfate aerosol drives contraction. BC, especially from Asia, is more efficient per unit radiative forcing than greenhouse gases in driving tropical expansion, particularly in the Northern Hemisphere. Tropical belt expansion (contraction) is associated with an increase (decrease) in extratropical static stability induced by absorbing (scattering) aerosol. Although a formal attribution is difficult, scaling the normalized expansion rates to the historical time period suggests that BC is the largest driver of the Northern Hemisphere tropical widening but with relatively large uncertainty

A Simple and Non-destructive Method for Chlorophyll Quantification of Chlamydomonas Cultures Using Digital Image Analysis

Growing interest in the use of microalgae as a sustainable feedstock to support a green, circular, bio-economy has led to intensive research and development initiatives aimed at increasing algal biomass production covering a wide range of scales. At the heart of this lies a common need for rapid and accurate methods to measure algal biomass concentrations. Surrogate analytical techniques based on chlorophyll content use solvent extraction methods for chlorophyll quantification, but these methods are destructive, time consuming and require careful disposal of the resultant solvent waste. Alternative non-destructive methods based on chlorophyll fluorescence require expensive equipment and are less suitable for multiple sampling of small cultures which need to be maintained under axenic growth conditions. A simple, inexpensive and non-destructive method to estimate chlorophyll concentration of microalgal cultures in situ from digital photographs using the RGB color model is presented. Green pixel intensity and chlorophyll a, b and total chlorophyll concentration, measured by conventional means, follow a strong linear relationship (R2 = 0.985–0.988). In addition, the resulting standard curve was robust enough to accurately estimate chlorophyll concentration despite changes in sample volume, pH and low concentrations of bacterial contamination. In contrast, use of the same standard curve during nitrogen deprivation (causing the accumulation of neutral lipids) or in the presence of high quantities of bacterial contamination led to significant errors in chlorophyll estimation. The low requirement for equipment (i.e., a simple digital camera, available on smartphones) and widely available standard software for measuring pixel intensity make this method suitable for both laboratory and field-based work, particularly in situations where sample, qualified personnel and/or equipment is limited. By following the methods described here it should be possible to produce a standard curve for chlorophyll analysis in a wide range of testing conditions including different microalga cultures, culture vessel and photographic set up in any particular laboratory

High-threshold mechanosensitive ion channels blocked by a novel conopeptide mediate pressure-evoked pain

Little is known about the molecular basis of somatosensory mechanotransduction in mammals. We screened a library of peptide toxins for effects on mechanically activated currents in cultured dorsal root ganglion neurons. One conopeptide analogue, termed NMB-1 for noxious mechanosensation blocker 1, selectively inhibits (IC50 1 µM) sustained mechanically activated currents in a subset of sensory neurons. Biotinylated NMB-1 retains activity and binds selectively to peripherin-positive nociceptive sensory neurons. The selectivity of NMB-1 was confirmed by the fact that it has no inhibitory effects on voltage-gated sodium and calcium channels, or ligand-gated channels such as acid-sensing ion channels or TRPA1 channels. Conversely, the tarantula toxin, GsMTx-4, which inhibits stretch-activated ion channels, had no effects on mechanically activated currents in sensory neurons. In behavioral assays, NMB-1 inhibits responses only to high intensity, painful mechanical stimulation and has no effects on low intensity mechanical stimulation or thermosensation. Unexpectedly, NMB-1 was found to also be an inhibitor of rapid FM1-43 loading (a measure of mechanotransduction) in cochlear hair cells. These data demonstrate that pharmacologically distinct channels respond to distinct types of mechanical stimuli and suggest that mechanically activated sustained currents underlie noxious mechanosensation. NMB-1 thus provides a novel diagnostic tool for the molecular definition of channels involved in hearing and pressure-evoked pain

Distribution of macroinvertebrate communities across surface and groundwater habitats in response to hydrological variability

Macroinvertebrate communities are strongly influenced by hydrological variability in surface waters. However, the response of these communities in corresponding groundwater-dependent habitats is not well understood. This study characterised the macroinvertebrate fauna and physicochemical characteristics of a chalk aquifer and its rivers in southern England. Over one year, samples were collected from five paired benthic-hyporheic sites located in perennial or temporary rivers, and a further seven phreatic sites in the surrounding aquifer. The study was preceded by a period of below average rainfall, providing an opportunity to assess the response of macro-invertebrate communities to unseasonal declines in river discharge and groundwater levels. Benthic, hyporheic and phreatic habitats each supported a distinct macroinvertebrate community, with the hyporheic habitat support- ing both epigean taxa and stygofauna. As discharge declined, the composition of these communities changed. In particular, the abundance of the epigean amphipod Gammarus pulex was higher in hyporheic than benthic habitats during periods of low river discharge, suggesting potential refuge-seeking behaviour. Similarly, fluctuations in the abundance and distribution of two stygofauna, Crangonyx subterraneus and Niphargus fontanus, coincided with marked changes in groundwater levels, suggesting that the contraction of available habitat and changes in connectivity also influenced the phreatic community. The variable distribution of macroinvertebrates between these habitats, especially in response to hydrological variability, suggests a dynamic connection between the river and its aquifer. This connection is an important consideration for the assessment and conservation management of both surface and groundwater communities and may help underpin integrated, catchment-based management, especially in river systems with temporary reaches

Children With Developmental Coordination Disorder Exhibit Greater Stepping Error Despite Similar Gaze Patterns and State Anxiety Levels to Their Typically Developing Peers

This study examined stepping accuracy, gaze behavior, and state-anxiety in children with (N = 21, age M = 10.81, SD = 1.89) and without (N = 18, age M = 11.39, SD = 2.06) developmental coordination disorder (DCD) during an adaptive locomotion task. Participants walked at a self-selected pace along a pathway, placing their foot into a raised rectangular floor-based target box followed by either no obstacles, one obstacle, or two obstacles. Stepping kinematics and accuracy were determined using three-dimensional motion capture, whilst gaze was determined using mobile eye-tracking equipment. The children with DCD displayed greater foot placement error and variability when placing their foot within the target box and were more likely to make contact with its edges than their typically developing (TD) peers. The DCD group also displayed greater variability in the length and width of their steps in the approach to the target box. No differences were observed between groups in any of the gaze variables measured, in mediolateral velocity of the center of mass during the swing phase into the target box, or in the levels of self-reported state-anxiety experienced prior to facing each task. We therefore provide the first quantifiable evidence that deficits to foot placement accuracy and precision may be partially responsible for the increased incidence of trips and falls in DCD, and that these deficits are likely to occur independently from gaze behavior and state-anxiety