Laboratory study of spectral induced polarization responses of magnetite - Fe2+ redox reactions in porous media

Spectral Induced Polarization (SIP) phase anomalies in field surveys at contaminated sites have previously been shown to correlate with the occurrence of chemically reducing conditions and/or semiconductive minerals, but the reasons for this are not fully understood. We report a systematic laboratory investigation of the role of the semiconductive mineral magnetite and its interaction with redoxactive versus redox-inactive ions in producing such phase anomalies. The SIP responses of quartz sand with 5% magnetite in solutions containing redox-inactive Ca2+, and Ni2+, versus redox-active Fe2+ were measured across the pH ranges corresponding to adsorption of these metals to magnetite. With redox inactive ions Ca2+ and Ni2+, SIP phase response showed no changes across the pH range 4 to10, corresponding to their adsorption, showing ~30 mrad anomalies peaking at ~59 to 74 Hz. These large phase anomalies are probably caused by polarization of the magnetite-solution interfaces. With the redox-active ion Fe2+, frequency of peak phase res onse decreased progressively from ~46 to ~3 Hz as effluent pH increased from 4 to 7, corresponding to progressive adsorption of Fe2+ to the magnetite surface. The latter frequency (3 Hz) corresponds approximately with those of phase anomalies detected in field surveys reported elsewhere. We conclude that pH sensitivity arises from redox reactions between Fe2+ and magnetite surfaces, with transfer of electrical charge through the bulk mineral, as reported in other laboratory investigations. Our results confirm that SIP measurements are sensitive to redox reactions involving charge transfers between adsorbed ions and semiconductive minerals. Phase anomalies seen in field surveys of groundwater contamination and biostimulation may therefore be indicative of iron-reducing conditions, when semiconductive iron minerals such as magnetite are present

Resolving the energy and temperature dependence of C₆ H₆ ∗ collisional relaxation via time-dependent bath temperature measurements

The relaxation of highly vibrationally excited benzene, generated by 193 nm laser excitation, was studied using the transient rotational-translational temperature rise of the N2 bath, which was measured by proxy using two-line laser induced fluorescence of seeded NO. The resulting experimentally measured time-dependent N2 temperature rises were modeled with MultiWell based simulations of Collisional Energy Transfer (CET) from benzene vibration to N2 rotation-translation. We find that the average energy transferred in benzene deactivating collisions depends linearly on the internal energy of the excited benzene molecules and depends approximately linearly on the N2 bath temperature between 300 K and 600 K. The results are consistent with experimental studies and classical trajectory calculations of CET in similar systems

A unified allosteric/torpedo mechanism for transcriptional termination on human protein-coding genes.

This is the final version. Available on open access from Cold Spring Harbor Laboratory Press via the DOI in this record. The allosteric and torpedo models have been used for 30 yr to explain how transcription terminates on protein-coding genes. The former invokes termination via conformational changes in the transcription complex and the latter proposes that degradation of the downstream product of poly(A) signal (PAS) processing is important. Here, we describe a single mechanism incorporating features of both models. We show that termination is completely abolished by rapid elimination of CPSF73, which causes very extensive transcriptional readthrough genome-wide. This is because CPSF73 functions upstream of modifications to the elongation complex and provides an entry site for the XRN2 torpedo. Rapid depletion of XRN2 enriches these events that we show are underpinned by protein phosphatase 1 (PP1) activity, the inhibition of which extends readthrough in the absence of XRN2. Our results suggest a combined allosteric/torpedo mechanism, in which PP1-dependent slowing down of polymerases over termination regions facilitates their pursuit/capture by XRN2 following PAS processing.Lister Institute of Preventative MedicineWellcome Trus

A cluster-randomized, placebo-controlled, maternal vitamin a or beta-carotene supplementation trial in bangladesh: design and methods

<p>Abstract</p> <p>Background</p> <p>We present the design, methods and population characteristics of a large community trial that assessed the efficacy of a weekly supplement containing vitamin A or beta-carotene, at recommended dietary levels, in reducing maternal mortality from early gestation through 12 weeks postpartum. We identify challenges faced and report solutions in implementing an intervention trial under low-resource, rural conditions, including the importance of population choice in promoting generalizability, maintaining rigorous data quality control to reduce inter- and intra- worker variation, and optimizing efficiencies in information and resources flow from and to the field.</p> <p>Methods</p> <p>This trial was a double-masked, cluster-randomized, dual intervention, placebo-controlled trial in a contiguous rural area of ~435 sq km with a population of ~650,000 in Gaibandha and Rangpur Districts of Northwestern Bangladesh. Approximately 120,000 married women of reproductive age underwent 5-weekly home surveillance, of whom ~60,000 were detected as pregnant, enrolled into the trial and gave birth to ~44,000 live-born infants. Upon enrollment, at ~ 9 weeks' gestation, pregnant women received a weekly oral supplement containing vitamin A (7000 ug retinol equivalents (RE)), beta-carotene (42 mg, or ~7000 ug RE) or a placebo through 12 weeks postpartum, according to prior randomized allocation of their cluster of residence. Systems described include enlistment and 5-weekly home surveillance for pregnancy based on menstrual history and urine testing, weekly supervised supplementation, periodic risk factor interviews, maternal and infant vital outcome monitoring, birth defect surveillance and clinical/biochemical substudies.</p> <p>Results</p> <p>The primary outcome was pregnancy-related mortality assessed for 3 months following parturition. Secondary outcomes included fetal loss due to miscarriage or stillbirth, infant mortality under three months of age, maternal obstetric and infectious morbidity, infant infectious morbidity, maternal and infant micronutrient status, fetal and infant growth and prematurity, external birth defects and postnatal infant growth to 3 months of age.</p> <p>Conclusion</p> <p>Aspects of study site selection and its "resonance" with national and rural qualities of Bangladesh, the trial's design, methods and allocation group comparability achieved by randomization, field procedures and innovative approaches to solving challenges in trial conduct are described and discussed. This trial is registered with <url>http://Clinicaltrials.gov</url> as protocol NCT00198822.</p

The Emerging Scholarly Brain

It is now a commonplace observation that human society is becoming a coherent super-organism, and that the information infrastructure forms its emerging brain. Perhaps, as the underlying technologies are likely to become billions of times more powerful than those we have today, we could say that we are now building the lizard brain for the future organism.Comment: to appear in Future Professional Communication in Astronomy-II (FPCA-II) editors A. Heck and A. Accomazz

The communication of a secondary care diagnosis of autoimmune hepatitis to primary care practitioners: a population-based study

Background Autoimmune Hepatitis is a chronic liver disease which affects young people and can result in liver failure leading to death or transplantation yet there is a lack of information on the incidence and prevalence of this disease and its natural history in the UK. A means of obtaining this information is via the use of clinical databases formed of electronic primary care records. How reliably the diagnosis is coded in such records is however unknown. The aim of this study therefore was to assess the proportion of consultant hepatologist diagnoses of Autoimmune Hepatitis which were accurately recorded in General Practice computerised records. Methods Our study population were patients with Autoimmune Hepatitis diagnosed by consultant hepatologists in the Queens Medical Centre, Nottingham University Hospitals (UK) between 2004 and 2009. We wrote to the general practitioners of these patients to obtain the percentage of patients who had a valid READ code specific for Autoimmune Hepatitis. Results We examined the electronic records of 51 patients who had biopsy evidence and a possible diagnosis of Autoimmune Hepatitis. Forty two of these patients had a confirmed clinical diagnosis of Autoimmune Hepatitis by a consultant hepatologist: we contacted the General Practitioners of these patients obtaining a response rate of 90.5% (39/42 GPs). 37/39 of these GPs responded with coding information and 89% of these patients (33/37) used Read code J638.00 (Autoimmune Hepatitis) to record a diagnosis. Conclusions The diagnosis of Autoimmune Hepatitis made by a Consultant Hepatologist is accurately communicated to and electronically recorded by primary care in the UK. As a large proportion of cases of Autoimmune Hepatitis are recorded in primary care, this minimises the risk of introducing selection bias and therefore selecting cases using these data will be a valid method of conducting population based studies on Autoimmune Hepatitis

Non-statistical intermolecular energy transfer from vibrationally excited benzene in a mixed nitrogen-benzene bath.

A chemical dynamics simulation was performed to model experiments [N. A. West et al., J. Chem. Phys. 145, 014308 (2016)] in which benzene molecules are vibrationally excited to 148.1 kcal/mol within a N2-benzene bath. A significant fraction of the benzene molecules are excited, resulting in heating of the bath, which is accurately represented by the simulation. The interesting finding from the simulations is the non-statistical collisional energy transfer from the vibrationally excited benzene C6H6 * molecules to the bath. The simulations find that at ∼10-7 s and 1 atm pressure there are four different final temperatures for C6H6 * and the bath. N2 vibration is not excited and remains at the original bath temperature of 300 K. Rotation and translation degrees of freedom of both N2 and C6H6 in the bath are excited to a final temperature of ∼340 K. Energy transfer from the excited C6H6 * molecules is more efficient to vibration of the C6H6 bath than its rotation and translation degrees of freedom, and the final vibrational temperature of the C6H6 bath is ∼453 K, if the average energy of each C6H6 vibration mode is assumed to be RT. There is no vibrational equilibration between C6H6 * and the C6H6 bath molecules. When the simulations are terminated, the vibrational temperatures of the C6H6 * and C6H6 bath molecules are ∼537 K and ∼453 K, respectively. An important question is the time scale for complete energy equilibration of the C6H6 * and N2 and C6H6 bath system. At 1 atm and 300 K, the experimental V-T (vibration-translation) relaxation time for N2 is ∼10-4 s. The simulation time was too short for equilibrium to be attained, and the time for complete equilibration of C6H6 * vibration with translation, rotation, and vibration of the bath was not determined

Cooperative secretions facilitate host range expansion in bacteria

The majority of emergent human pathogens are zoonotic in origin, that is, they can transmit to humans from other animals. Understanding the factors underlying the evolution of pathogen host range is therefore of critical importance in protecting human health. There are two main evolutionary routes to generalism: organisms can tolerate multiple environments or they can modify their environments to forms to which they are adapted. Here we use a combination of theory and a phylogenetic comparative analysis of 191 pathogenic bacterial species to show that bacteria use cooperative secretions that modify their environment to extend their host range and infect multiple host species. Our results suggest that cooperative secretions are key determinants of host range in bacteria, and that monitoring for the acquisition of secreted proteins by horizontal gene transfer can help predict emerging zoonoses

A rationale for continuing mass antibiotic distributions for trachoma

BACKGROUND: The World Health Organization recommends periodic mass antibiotic distributions to reduce the ocular strains of chlamydia that cause trachoma, the world's leading cause of infectious blindness. Their stated goal is to control infection, not to completely eliminate it. A single mass distribution can dramatically reduce the prevalence of infection. However, if infection is not eliminated in every individual in the community, it may gradually return back into the community, so often repeated treatments are necessary. Since public health groups are reluctant to distribute antibiotics indefinitely, we are still in need of a proven long-term rationale. Here we use mathematical models to demonstrate that repeated antibiotic distributions can eliminate infection in a reasonable time period. METHODS: We fit parameters of a stochastic epidemiological transmission model to data collected before and 6 months after a mass antibiotic distribution in a region of Ethiopia that is one of the most severely affected areas in the world. We validate the model by comparing our predicted results to Ethiopian data which was collected biannually for two years past the initial mass antibiotic distribution. We use the model to simulate the effect of different treatment programs in terms of local elimination of infection. RESULTS: Simulations show that the average prevalence of infection across all villages progressively decreases after each treatment, as long as the frequency and coverage of antibiotics are high enough. Infection can be eliminated in more villages with each round of treatment. However, in the communities where infection is not eliminated, it returns to the same average level, forming the same stationary distribution. This phenomenon is also seen in subsequent epidemiological data from Ethiopia. Simulations suggest that a biannual treatment plan implemented for 5 years will lead to elimination in 95% of all villages. CONCLUSION: Local elimination from a community is theoretically possible, even in the most severely infected communities. However, elimination from larger areas may require repeated biannual treatments and prevention of re-introduction from outside to treated areas