Intrinsic Nature of Spontaneous Magnetic Fields in Superconductors with Time-Reversal Symmetry Breaking

We present a systematic investigation of muon-stopping states in superconductors that reportedly exhibit spontaneous magnetic fields below their transition temperatures due to time-reversal symmetry breaking. These materials include elemental rhenium, several intermetallic systems, and Sr_{2}RuO_{4}. We demonstrate that the presence of the muon leads to only a limited and relatively localized perturbation to the local crystal structure, while any small changes to the electronic structure occur several electron volts below the Fermi energy, leading to only minimal changes in the charge density on ions close to the muon. Our results imply that the muon-induced perturbation alone is unlikely to lead to the observed spontaneous fields in these materials, whose origin is more likely intrinsic to the time-reversal symmetry-broken superconducting state.

Origin of Magnetic Ordering in a Structurally Perfect Quantum Kagome Antiferromagnet

The ground state of the simple Heisenberg nearest-neighbor quantum kagome antiferromagnetic model is a magnetically disordered spin liquid, yet various perturbations may lead to fundamentally different states. Here we disclose the origin of magnetic ordering in the structurally perfect kagome material YCu_{3}(OH)_{6}Cl_{3}, which is free of the widespread impurity problem. Ab initio calculations and modeling of its magnetic susceptibility reveal that, similar to the archetypal case of herbertsmithite, the nearest-neighbor exchange is by far the dominant isotropic interaction. Dzyaloshinskii-Moriya (DM) anisotropy deduced from electron spin resonance, susceptibility, and specific-heat data is, however, significantly larger than in herbertsmithite. By enhancing spin correlations within kagome planes, this anisotropy is essential for magnetic ordering. Our study isolates the effect of DM anisotropy from other perturbations and unambiguously confirms the predicted phase diagram.

Using deterministic record linkage to link ambulance and emergency department data: is it possible without patient identifiers? A case study from the UK

INTRODUCTION

Routine linkage of emergency ambulance records with those from the emergency department is uncommon in the UK. Our study, known as the Pre-Hospital Emergency Department Data Linking Project (PHED Data), aimed to link records of all patients conveyed by a single emergency ambulance service to thirteen emergency departments in the UK from 2012-2016.

OBJECTIVES

We aimed to examine the feasibility and resource requirements of collecting de-identified emergency department patient record data and, using a deterministic matching algorithm, linking it to ambulance service data.

METHODS

We used a learning log to record contacts and activities undertaken by the research team to achieve data linkage. We also conducted semi-structured interviews with information management/governance staff involved in the process.

RESULTS

We found that five steps were required for successful data linkage for each hospital trust. The total time taken to achieve linkage was a mean of 65 weeks. A total of 958,057 emergency department records were obtained and, of these, 81% were linked to a corresponding ambulance record. The match rate varied between hospital trusts (50%-94%). Staff expressed strong enthusiasm for data linkage. Barriers to successful linkage were mainly due to inconsistencies between and within acute trusts in the recording of two ambulance event identifiers (CAD and call sign). Further data cleaning was required on emergency department fields before full analysis could be conducted. Ensuring the data was not re-identifiable limited validation of the matching method.

CONCLUSION

We conclude that deterministic record linkage based on the combination of two event identifiers (CAD and call sign) is possible. There is an appetite for data linkage in healthcare organisations but it is a slow process. Developments in standardising the recording of emergency department data are likely to improve the quality of the resultant linked dataset. This would further increase its value for providing evidence to support improvements in health care delivery.

HIGHLIGHTS

Ambulance records are rarely linked to other datasets; this study looks at the feasibility and resource requirement to use deterministic matching to link ambulance and emergency department data for patients conveyed by ambulance to the emergency department.It is possible to link these data, with an average match rate of 81% across 13 emergency departments and one large ambulance trust.All trusts approached provided match-able data and there was an appetite for data linkage; however, it was a long process taking an average of 65 weeks.We conclude that deterministic matching using no patient identifiers can be used in this setting.

Local magnetism, magnetic order and spin freezing in the 'nonmetallic metal' FeCrAs

We present the results of x-ray scattering and muon-spin relaxation ([Formula: see text]SR) measurements on the iron-pnictide compound FeCrAs. Polarized non-resonant magnetic x-ray scattering results reveal the 120° periodicity expected from the suggested three-fold symmetric, non-collinear antiferromagnetic structure. [Formula: see text]SR measurements indicate a magnetically ordered phase throughout the bulk of the material below [Formula: see text] K. There are signs of fluctuating magnetism in a narrow range of temperatures above [Formula: see text] involving low-energy excitations, while at temperatures well below [Formula: see text] behaviour characteristic of freezing of dynamics is observed, likely reflecting the effect of disorder in our polycrystalline sample. Using density functional theory we propose a distinct muon stopping site in this compound and assess the degree of distortion induced by the implanted muon.

Complex Low Energy Tetrahedral Polymorphs of Group IV Elements from First Principles

The energy landscape of carbon is exceedingly complex, hosting diverse and important metastable phases, including diamond, fullerenes, nanotubes, and graphene. Searching for structures, especially those with large unit cells, in this landscape is challenging. Here we use a combined stochastic search strategy employing two algorithms (ab initio random structure search and random sampling strategy combined with space group and graph theory) to apply connectivity constraints to unit cells containing up to 100 carbon atoms. We uncover three low energy carbon polymorphs (Pbam-32, P6/mmm, and I4[over ¯]3d) with new topologies, containing 32, 36, and 94 atoms in their primitive cells, respectively. Their energies relative to diamond are 96, 131, and 112  meV/atom, respectively, which suggests potential metastability. These three carbon allotropes are mechanically and dynamically stable, insulating carbon crystals with superhard mechanical properties. The I4[over ¯]3d structure possesses a direct band gap of 7.25 eV, which is the widest gap in the carbon allotrope family. Silicon, germanium, and tin versions of Pbam-32, P6/mmm, and I4[over ¯]3d also show energetic, dynamical, and mechanical stability. The computed electronic properties show that they are potential materials for semiconductor and photovoltaic applications.

Hyak mortality monitoring system: innovative sampling and estimation methods - proof of concept by simulation

Traditionally health statistics are derived from civil and/or vital registration. Civil registration in low- to middle-income countries varies from partial coverage to essentially nothing at all. Consequently the state of the art for public health information in low- to middle-income countries is efforts to combine or triangulate data from different sources to produce a more complete picture across both time and space - data amalgamation. Data sources amenable to this approach include sample surveys, sample registration systems, health and demographic surveillance systems, administrative records, census records, health facility records and others. We propose a new statistical framework for gathering health and population data - Hyak - that leverages the benefits of sampling and longitudinal, prospective surveillance to create a cheap, accurate, sustainable monitoring platform. Hyak has three fundamental components: Data amalgamation: A sampling and surveillance component that organizes two or more data collection systems to work together: (1) data from HDSS with frequent, intense, linked, prospective follow-up and (2) data from sample surveys conducted in large areas surrounding the Health and Demographic Surveillance System (HDSS) sites using informed sampling so as to capture as many events as possible;Cause of death: Verbal autopsy to characterize the distribution of deaths by cause at the population level; andSocioeconomic status (SES): Measurement of SES in order to characterize poverty and wealth. We conduct a simulation study of the informed sampling component of Hyak based on the Agincourt HDSS site in South Africa. Compared with traditional cluster sampling, Hyak's informed sampling captures more deaths, and when combined with an estimation model that includes spatial smoothing, produces estimates of both mortality counts and mortality rates that have lower variance and small bias.

A local Fock-exchange potential in Kohn-Sham equations

We derive and employ a local potential to represent the Fock exchange operator in electronic single-particle equations. This local Fock-exchange (LFX) potential is very similar to the exact exchange (EXX) potential in density functional theory (DFT). The practical software implementation of the two potentials (LFX and EXX) yields robust and accurate results for a variety of systems (semiconductors, transition metal oxides) where Hartree-Fock and popular approximations of DFT typically fail. This includes examples traditionally considered qualitatively inaccessible to calculations that omit correlation.

Induced thiacloprid insensitivity in honeybees (Apis mellifera L.) is associated with up-regulation of detoxification genes

Honey bees, Apis mellifera, are markedly less sensitive to neonicotinoid insecticides containing a cyanoimino pharmacophore than to those with a nitroimino group. Although previous work has suggested that this results from enhanced metabolism of the former by detoxification enzymes, the specific enzyme(s) involved remain to be characterized. In this work, a pretreatment of honey bees with a sublethal dose of thiacloprid resulted in induced insensitivity to the same compound immediately following thiacloprid feeding. A longer pretreatment time resulted in no, or increased, sensitivity. Transcriptome profiling, using microarrays, identified a number of genes encoding detoxification enzymes that were over-expressed significantly in insecticide-treated bees compared with untreated controls. These included five P450s, CYP6BE1, CYP305D1, CYP6AS5, CYP315A1, CYP301A1, and a carboxyl/cholinesterase (CCE) CCE8. Four of these P450s were functionally expressed in Escherichia coli and their ability to metabolize thiacloprid examined by liquid chromatography-mass spectrometry (LC-MS) analysis.

Muon-spin relaxation study of the double perovskite insulators Sr2 BOsO6 (B = Fe, Y, ln)

We present the results of zero-field muon-spin relaxation measurements made on the double perovskite insulators Sr2 BOsO6 (B = Fe,Y, In). Spontaneous muon-spin precession indicative of quasistatic long range magnetic ordering is observed in Sr2FeOsO6 within the AF1 antiferromagnetic phase for temperatures below [Formula: see text] K. Upon cooling below T2≈67 K the oscillations cease to be resolvable owing to the coexistence of the AF1 and AF2 phases, which leads to a broader range of internal magnetic fields. Using density functional calculations we identify a candidate muon stopping site within the unit cell, which dipole field simulations show to be consistent with the proposed magnetic structure. The possibility of incommensurate magnetic ordering is discussed for temperatures below TN = 53 K and 25 K for Sr2YOsO6 and Sr2InOsO6, respectively.

A national survey of parent perspectives on use of patient portals for their children's health care

OBJECTIVES

To assess parents' current utilization and future willingness to use patient portals to interact with their child's health care provider.

METHODS

A cross-sectional survey of a nationally representative sample of US parents was conducted using an established online panel. Bivariate analyses assessed associations between current utilization and future willingness to use patient portals, parental concerns, and demographic variables.

RESULTS

Among the 1,420 parent respondents, 40% did not know whether their child's health practice offers the option of setting up a patient portal for their child. Of the 21% of parents who reported being offered the option of setting up a patient portal for their child, 59% had done so. Among parents who had the option but chose not to set up a patient portal for their child, lack of time and low perceived need were the main reasons cited. Current use and likelihood of future use was highest for viewing lab results and immunization records. The most common concern about patient portals was the security of the child portal system.

CONCLUSIONS

Current use of patient portals by parents is low. Only about half of parents currently using or likely to use a portal perceive value in using portals for certain tasks, which suggests that providers will need to continue traditional communication mechanisms to reach their entire patient population.

Splash dispersal of Phyllosticta citricarpa conidia from infected citrus fruit

Rain-splash dispersal of Phyllosticta citricarpa (syn. Guignardia citricarpa) conidia (pycnidiospores) from infected oranges was studied in still air and combined with wind. High power microscopy demonstrated the presence of conidia in splash droplets from diseased oranges, which exuded conidia for over one hour during repeated wetting. The largest (5 mm) incident drops produced the highest splashes (up to 41.0 cm). A linear-by-quadratic surface model predicted highest splashes to be 41.91 cm at a horizontal distance of 25.97 cm from the target orange. Large splash droplets contained most conidia (4-5.5 mm splashes averaged 308 conidia), but were splashed <30 cm horizontal distance. Most (80-90%) splashes were <1 mm diameter but carried only 0-4 conidia per droplet. In multiple splash experiments, splashes combined to reach higher maxima (up to 61.7 cm; linear-by-quadratic surface model prediction, 62.1 cm) than in the single splash experiments. In combination with wind, higher wind speeds carried an increasing proportion of splashes downwind travelling horizontally at least 8 m at the highest wind speed tested (7 m/s), due to a small proportion of droplets (<1 mm) being aerosolised. These experiments suggest that P. citricarpa conidia can be dispersed from infected oranges by splashes of water in rainfall events.

Methylated Glutathione S-transferase 1 (mGSTP1) is a potential plasma free DNA epigenetic marker of prognosis and response to chemotherapy in castrate-resistant prostate cancer

Background:

Glutathione S-transferase 1 (GSTP1) inactivation is associated with CpG island promoter hypermethylation in the majority of prostate cancers (PCs). This study assessed whether the level of circulating methylated GSTP1 (mGSTP1) in plasma DNA is associated with chemotherapy response and overall survival (OS).

Methods:

Plasma samples were collected prospectively from a Phase I exploratory cohort of 75 men with castrate-resistant PC (CRPC) and a Phase II independent validation cohort (n=51). mGSTP1 levels in free DNA were measured using a sensitive methylation-specific PCR assay.

Results:

The Phase I cohort identified that detectable baseline mGSTP1 DNA was associated with poorer OS (HR, 4.2 95% CI 2.1–8.2; P<0.0001). A decrease in mGSTP1 DNA levels after cycle 1 was associated with a PSA response (P=0.008). In the Phase II cohort, baseline mGSTP1 DNA was a stronger predictor of OS than PSA change after 3 months (P=0.02). Undetectable plasma mGSTP1 after one cycle of chemotherapy was associated with PSA response (P=0.007).

Conclusions:

We identified plasma mGSTP1 DNA as a potential prognostic marker in men with CRPC as well as a potential surrogate therapeutic efficacy marker for chemotherapy and corroborated these findings in an independent Phase II cohort. Prospective Phase III assessment of mGSTP1 levels in plasma DNA is now warranted.

Circulating microRNAs are associated with docetaxel chemotherapy outcome in castration-resistant prostate cancer

Background:

Docetaxel is the first-line chemotherapy for castration-resistant prostate cancer (CRPC). However, response rates are ∼50% and determined quite late in the treatment schedule, thus non-responders are subjected to unnecessary toxicity. The potential of circulating microRNAs as early biomarkers of docetaxel response in CRPC patients was investigated in this study.

Methods:

Global microRNA profiling was performed on docetaxel-resistant and sensitive cell lines to identify candidate circulating microRNA biomarkers. Custom Taqman Array MicroRNA cards were used to measure the levels of 46 candidate microRNAs in plasma/serum samples, collected before and after docetaxel treatment, from 97 CRPC patients.

Results:

Fourteen microRNAs were associated with serum prostate-specific antigen (PSA) response or overall survival, according to Mann–Whitney U or log-rank tests. Non-responders to docetaxel and patients with shorter survival generally had high pre-docetaxel levels of miR-200 family members or decreased/unchanged post-docetaxel levels of miR-17 family members. Multivariate Cox regression with bootstrapping validation showed that pre-docetaxel miR-200b levels, post-docetaxel change in miR-20a levels, pre-docetaxel haemoglobin levels and visceral metastasis were independent predictors of overall survival when modelled together.

Conclusions:

Our study suggests that circulating microRNAs are potential early predictors of docetaxel chemotherapy outcome, and warrant further investigation in clinical trials.

Cardiac Troponin T Following Anthracycline Chemotherapy in Children and Adolescents

Cardiac troponin T (CTT) is elevated acutely in animal models of anthracycline cardiotoxicity. We assessed CTT release in children receiving anthracylines using a third generation assay. We measured CTT in 30 children receiving anthracycline chemotherapy. A total of 3 samples were taken from each child: 1) prior to, 2) immediately after and 3) between 24-48 hours after the infusion. The dose range given during the measurements of cardiac troponin T was 15-60 (median 25) mg/m(2) and the previous exposure ranged from 0-300 (median 150) mg/m(2). Not one child had a detectable CTT level at any time. This study shows a lack of acute elevation CTT following anthracycline administration. In this respect it is unlikely that early estimation of CTT using this modern assay will be useful for screening for anthracycline cadiomyopathy. Further studies using a third generation assay, are, however, indicated to determine whether delayed elevation of CTT occurs.

Three-point appraisal of genetic linkage maps

This paper develops a simple diagnostic for the investigation of uncertainty within genetic linkage maps using a Bayesian procedure. The method requires only the genotyping data and the proposed genetic map, and calculates the posterior probability for the possible orders of any set of three markers, accounting for the presence of genotyping error (mistyping) and for missing genotype data. The method uses a Bayesian approach to give insight into conflicts between the order in the proposed map and the genotype scores. The method can also be used to assess the accuracy of a genetic map at different genomic scales and to assess alternative potential marker orders. Simulation and two case studies were used to illustrate the method. In the first case study, the diagnostic revealed conflicts in map ordering for short inter-marker distances that were resolved at a distance of 8-12 cM, except for a set of markers at the end of the linkage group. In the second case study, the ordering did not resolve as distances increase, which could be attributed to regions of the map where many individuals were untyped.

The high-pressure electronic structure of the [Ni(ptdt)2] organic molecular conductor

The electronic structure of the single component molecular crystal [Ni(ptdt)(2)] (ptdt = propylenedithiotetrathiafulvalenedithiolate) is determined at ambient and high pressure using density functional theory. The electronic structure of this crystal is found to be of the "crossing bands" type with respect to the dispersion of the HOMO and LUMO, resulting in a small, non-zero density of states at the Fermi energy at ambient pressure, indicating that this crystal is a "poor quality" metal, and is consistent with the crystal's resistivity exhibiting a semiconductor-like temperature dependence. The ambient pressure band structure is found to be predominantly one-dimensional, reflecting enhanced intermolecular interactions along the [100] stacking direction. Our calculations indicate that the band structure becomes two-dimensional at high pressures and reveals the role of shortened intermolecular contacts in this phenomenon. The integrity of the molecular structure is found to be maintained up to at least 22 GPa. The electronic structure is found to exhibit a crossing bands nature up to 22 GPa, where enhanced intermolecular interactions increase the Brillouin zone centre HOMO-LUMO gap from 0.05 eV at ambient pressure to 0.15 eV at 22 GPa; this enhanced HOMO-LUMO interaction ensures that enhancement of a metallic state in this crystal cannot be simply achieved through the application of pressure, but rather requires some rearrangement of the molecular packing. Enhanced HOMO-LUMO interactions result in a small density of states at the Fermi energy for the high pressure window 19.8-22 GPa, and our calculations show that there is no change in the nature of the electronic structure at the Fermi energy for these pressures. We correspondingly find no evidence of an electronic semiconducting-metal insulator transition for these pressures, contrary to recent experimental evidence [Cui et al., J. Am. Chem. Soc. 131, 6358 (2009)].

Mesocosm experiments to assess the transmission of Pandora neoaphidis within simple and mixed field margins and over the crop-margin interface

Although considerable research on the development of agri-environment schemes has focussed on the value of managed field margins as reservoirs for arthropod natural enemies, their potential as reservoirs of entomopathogenic fungi has received less attention. Whether field margins that are most beneficial for arthropod natural enemies are the same as those for entomopathogenic fungi is unknown. Here, within glasshouse mesocosms, we assessed the reproductive success of the aphid-specific entomopathogenic fungus Pandora neoaphidis on aphids in a 'simple margin' containing one plant species and on the same species of aphid in a 'mixed margin' containing seven plant species. These assessments were done in the presence of Aphidius ervi, a hymenopteran parasitoid of aphids regarded as being a key species to conserve in agri-environment schemes in the UK. When only the plants initially infested with aphids were assessed, transmission of P. neoaphidis was significantly greater (p<0.001) in the mixed margin as was parasitisation by A. ervi (p<0.05). However, when all of the plants in the mesocosms were assessed, transmission of P. neoaphidis remained greater in the mixed margin (p<0.05) whereas parasitisation by A. ervi was greater in the simple margin (p<0.05). This difference may be due to aphid dispersal which was greater in the simple margin thereby benefitting the actively foraging parasitoid whereas clustering of aphids in the mixed margin benefited the passively dispersed fungus. In a second mesocosm experiment, the movement of P. neoaphidis over the crop-margin interface was similar to that of A. ervi despite the fungus only being passively dispersed in contrast to the actively foraging parasitoid. The results presented here indicate that, although the optimal plant composition of field margins may differ for P. neoaphidis and A. ervi, both species can co-exist and reproduce in field margins and will move over the crop-margin interface. Managed field margins that benefit both key arthropod and key microbial enemies have potential for enhancing pest control in associated crops.

Intraguild interactions between the entomopathogenic fungus Pandora neoaphidis and an aphid predator and parasitoid at the population scale

The interactions that occur between the entomopathogenic fungus Pandora neoaphidis and a predator (Coccinella septempunctata) and a parasitoid (Aphidius ervi) were assessed in microcosm and polytunnel experiments. Transmission of P. neoaphidis to the pea aphid, Acyrthosiphon pisum, was enhanced in the presence of both C. septempunctata and A. ervi in microcosm experiments done under fixed abiotic conditions. In contrast, the reproductive success of A. ervi was reduced in the presence of P. neoaphidis. Despite the increased fungal transmission in the presence of C. septempunctata, there was no additional decrease in the aphid population indicating that P. neoaphidis is functionally redundant in the presence of the coccinellid. In polytunnel experiments the reproductive success of A. ervi was not affected by P. neoaphidis. These results do not support those of the microcosm and may be due to the more natural abiotic conditions in the polytunnel reducing the competitive advantage of the fungus. Microcosms therefore provide an arena in which the interactions between fungal pathogens and other aphid-natural enemies can be assessed however, further assessments at increased spatial scales under more natural abiotic conditions are also required to accurately determine the outcome of these interactions.

Long-range epigenetic silencing at 2q14.2 affects most human colorectal cancers and may have application as a non-invasive biomarker of disease

Large chromosomal regions can be suppressed in cancer cells as denoted by hypermethylation of neighbouring CpG islands and downregulation of most genes within the region. We have analysed the extent and prevalence of long-range epigenetic silencing at 2q14.2 (the first and best characterised example of coordinated epigenetic remodelling) and investigated its possible applicability as a non-invasive diagnostic marker of human colorectal cancer using different approaches and biological samples. Hypermethylation of at least one of the CpG islands analysed (EN1, SCTR, INHBB) occurred in most carcinomas (90%), with EN1 methylated in 73 and 40% of carcinomas and adenomas, respectively. Gene suppression was a common phenomenon in all the tumours analysed and affected both methylated and unmethylated genes. Detection of methylated EN1 using bisulfite treatment and melting curve (MC) analysis from stool DNA in patients and controls resulted in a predictive capacity of, 44% sensitivity in positive patients (27% of overall sensitivity) and 97% specificity. We conclude that epigenetic suppression along 2q14.2 is common to most colorectal cancers and the presence of a methylated EN1 CpG island in stool DNA might be used as biomarker of neoplastic disease.

Effect of seasonal abiotic conditions and field margin habitat on the activity of Pandora neoaphidis inoculum on soil

The ability of the aphid pathogenic fungus Pandora neoaphidis to remain active in the absence of a resting stage through a combination of continuous infection and as conidia deposited on soil was assessed alongside the potential for planted field margins to act as a refuge for the fungus. P. neoaphidis was able to infect the pea aphid, Acyrthosiphon pisum, when maintained under controlled conditions that simulated those that occur seasonally in the UK. Although there was a significant inverse relationship between temperature and time-to-kill, with death occurring after 4.2, 6.9 and 13.6 days when maintained under fluctuating summer, autumn and winter temperatures, respectively, there were no additional statistically significant effects of photoperiod. The activity of inoculum on soil was indirectly assessed by baiting with A. pisum. Under controlled conditions P. neoaphidis remained active on soil and was able to infect aphids for up to 80 days. However, the percentage of aphids that became infected decreased from 76% on day 1 to 11% on day 80. Whereas there was little difference in the activity of conidia that had been maintained at 4 degrees C and 10 degrees C, activity at 18 degrees C was considerably reduced. Under field conditions the activity of inoculum was strongly influenced by season. On day 49 there was little or no activity during spring, summer or winter. However, during autumn a mean proportion of 0.08 aphids still became infected with P. neoaphidis. Margin type did not affect the activity of conidia nor was there a difference in activity between blocks that had regenerated naturally and those that had been planted. These results suggest that P. neoaphidis can infect aphids and remain active on soil under the abiotic conditions that occur seasonally in the UK and that this fungus may be able to persist annually without a resting stage.

Variable levels of carry over on platelet counts < or = 20 x 10(9)/l with the Bayer Advia 120

Accurate platelet counts are essential for the safe management of severe thrombocytopenia (platelet counts < or = 20 x 10(9)/l). The effect of carry over on platelet counting in severe thrombocytopenia was investigated by performing counts before and after saline rinses on three Bayer Advia 120 automated blood counters. Counts were performed in both primary and manual closed tube system modes on two instruments and in manual open tube mode on a third. A total of 194 samples with platelet counts < or = 20 x 10(9)/l were studied. First counts were significantly higher in all groups. The magnitude of the difference varied both by analyser and counting mode. Carry over was minimal with one analyser in primary mode and second counts were on average only 5.5% lower; on a second analyser in manual closed tube system mode second counts were on average 37.7% lower. A first count of > or = 10 x 10(9)/l fell to <10 x 10(9)/l on the second count in 35 of 145 samples (24.1%). In five such samples, all tested on one analyser, the second count was <50% of the value of the first count. Two of 49 (4.1%) first counts of <10 x 10(9)/l increased to > or = 10 x 10(9)/l on repeat. These results show a variable and often potentially clinically important carry-over effect on severely thrombocytopenic samples using the Advia 120.

Nematicidal effects of cysteine proteinases against sedentary plant parasitic nematodes

Cysteine proteinases from the fruit and latex of plants, such as papaya, pineapple and fig, have previously been shown to have substantial anthelmintic efficacy, in vitro and in vivo, against a range of animal parasitic nematodes. In this paper, we describe the in vitro effects of these plant extracts against 2 sedentary plant parasitic nematodes of the genera Meloidogyne and Globodera. All the plant extracts examined caused digestion of the cuticle and decreased the activity of the tested nematodes. The specific inhibitor of cysteine proteinases, E-64, blocked this activity completely, indicating that it was essentially mediated by cysteine proteinases. In vitro, plant cysteine proteinases are active against second-stage juveniles of M. incognita and M. javanica, and some cysteine proteinases also affect the second-stage juveniles of Globodera rostochiensis. It is not known yet whether these plant extracts will interfere with, or prevent invasion of, host plants.

Statistical models to evaluate invertebrate-plant trophic interactions in arable systems

Over the past 40 years there have been marked shifts in arable farmland management that are widely believed to have had a considerable impact on flowering plants and invertebrates and the small mammals and birds that rely upon them. It is not yet possible to predict the dynamics of plants and invertebrates either with past or future changes in farmland management. This study investigates whether a basic invertebrate classification, formed of broad trophic groups, can be used to describe interactions between invertebrates and their resource plants and evaluate management impacts for genetically modified, herbicide-tolerant (GMHT) and conventional herbicide management in both spring- and winter-sown oilseed rape. It is argued that the analyses validate trophic-based approaches for describing the dynamics of invertebrates in farmland and that linear models might be used to describe the changes in invertebrate trophic group abundance in farmland when driven by primary producer abundance or biomass and interactions between invertebrates themselves. The analyses indicate that invertebrate dynamics under GMHT management are not unique, but similar to conventional management occurring over different resource ranges, and that dynamics differed considerably between spring- and winter-sown oilseed rape. Thus, herbicide management was of much lower impact on trophic relationships than sowing date. Results indicate that invertebrate dynamics in oilseed rape are regulated by a combination of top-down and bottom-up trophic processes.

Ecotypes of the model legume Lotus japonicus vary in their interaction phenotypes with the root-knot nematode Meloidogyne incognita

BACKGROUND AND AIMS

Knowledge of host factors affecting plant-nematode interactions is scarce. Here, relevant interaction phenotypes between a nodulating model host, Lotus japonicus, and the endoparasitic root-knot nematode Meloidogyne incognita are assessed via a genetic screen.

METHODS

Within an alpha experimental design, 4-week-old replicate plants from 60 L. japonicus ecotypes were inoculated with 1000 nematodes from a single egg mass population, and evaluated for galling and nematode egg masses 6 weeks after inoculation.

KEY RESULTS

Statistical analysis of data for 57 ecotypes showed that ecotype susceptibilities ranged from 3.5 to 406 galls per root, and correlated strongly (r = 0.8, P < 0.001, log scale) with nematode reproduction (ranging from 0.6 to 34.5 egg masses per root). Some ecotypes, however, showed a significant discrepancy between disease severity and nematode reproduction. Necrosis and developmental malformations were observed in other infected ecotypes.

CONCLUSIONS

The first evidence is provided of significant variability in the interactions between L. japonicus and root-knot nematodes that may have further implications for the genetic dissection and characterization of host pathways involved in nematode parasitism and, possibly, in microbial symbiosis.

Effects of genetically modified herbicide-tolerant cropping systems on weed seedbanks in two years of following crops

The Farm Scale Evaluations (FSEs) showed that genetically modified herbicide-tolerant (GMHT) cropping systems could influence farmland biodiversity because of their effects on weed biomass and seed production. Recently published results for winter oilseed rape showed that a switch to GMHT crops significantly affected weed seedbanks for at least 2 years after the crops were sown, potentially causing longer-term effects on other taxa. Here, we seek evidence for similar medium-term effects on weed seedbanks following spring-sown GMHT crops, using newly available data from the FSEs. Weed seedbanks following GMHT maize were significantly higher than following conventional varieties for both the first and second years, while by contrast, seedbanks following GMHT spring oilseed rape were significantly lower over this period. Seedbanks following GMHT beet were smaller than following conventional crops in the first year after the crops had been sown, but this difference was much reduced by the second year for reasons that are not clear. These new data provide important empirical evidence for longer-term effects of GMHT cropping on farmland biodiversity.

Denaturing gradient gel electrophoresis can rapidly display the bacterial diversity contained in 16S rDNA clone libraries

Two different strategies for molecular analysis of bacterial diversity, 16S rDNA cloning and denaturing gradient gel electrophoresis (DGGE), were combined into a single protocol that took advantage of the best attributes of each: the ability of cloning to package DNA sequence information and the ability of DGGE to display a community profile. In this combined protocol, polymerase chain reaction products from environmental DNA were cloned, and then DGGE was used to screen the clone libraries. Both individual clones and pools of randomly selected clones were analyzed by DGGE, and these migration patterns were compared to the conventional DGGE profile produced directly from environmental DNA. For two simple bacterial communities (biofilm from a humics-fed laboratory reactor and planktonic bacteria filtered from an urban freshwater pond), pools of 35-50 clones produced DGGE profiles that contained most of the bands visible in the conventional DGGE profiles, indicating that the clone pools were adequate for identifying the dominant genotypes. However, DGGE profiles of two different pools of 50 clones from a lawn soil clone library were distinctly different from each other and from the conventional DGGE profile, indicating that this small number of clones poorly represented the bacterial diversity in soil. Individual clones with the same apparent DGGE mobility as prominent bands in the humics reactor community profiles were sequenced from the clone plasmid DNA rather than from bands excised from the gel. Because a longer fragment was cloned (approximately 1500 bp) than was actually analyzed in DGGE (approximately 350 bp), far more sequence information was available using this approach that could have been recovered from an excised gel band. This clone/DGGE protocol permitted rapid analysis of the microbial diversity in the two moderately complex systems, but was limited in its ability to represent the diversity in the soil microbial community. Nonetheless, clone/DGGE is a promising strategy for fractionating diverse microbial communities into manageable subsets consisting of small pools of clones.

Reactivation of latent hepatitis B virus infection with HIV-related immunosuppression

The effect of HIV-related immunosuppression and antiretroviral therapy on the reactivation of latent hepatitis B virus (HBV) infection is unclear. We report four patients with advanced HIV-related immunosuppression and abnormal liver function tests who had evidence of HBV reactivation. Reclearance of hepatitis B occurred in two cases with HIV treatment regimens not containing lamivudine, suggesting that improved immune function may be responsible. In three cases, HBV reactivation was recognized during investigation for abnormal liver function initially attributed to drug toxicity. The possibility of HBV reactivation must be considered in the differential diagnosis of abnormal liver function in cases with advanced HIV.

Effect of fungal infection on the reproductive potential of aphids and their progeny

The effect of infection by Pandora neoaphidis and Beauveria bassiana on the reproductive potential of the pea aphid, Acyrthosiphon pisum, and their progeny was assessed. Infection by either P. neoaphidis or B. bassiana reduced the number of nymphs produced within 24 h of inoculation and over the entire infection period compared to uninfected aphids. However, infection by either P. neoaphidis or B. bassiana for 24 or 72 h did not alter the intrinsic rate of increase of the host aphid's progeny. Therefore, fungal infection appears to have no indirect effects on the fitness of the host's progeny.

Wheat containing snowdrop lectin (GNA) does not affect infection of the cereal aphid Metopolophium dirhodum by the fungal natural enemyPandora neoaphidis

Studies were carried out to determine if susceptibility of the cereal aphid Metopolophium dirhodum to the fungus Pandora neoaphidis was affected by wheat expressing snowdrop lectin (GNA). Aphid infection did not differ significantly between the transgenic GNA and non-transformed lines (91 and 82%, respectively). Fecundity also did not differ between aphids on the two lines, and was ca. 18 nymphs adult(-1). Time to infection was ca. 5 days for M. dirhodum on both lines in two of three assays. Our results indicate that wheat expressing GNA would not compromise the efficacy of P. neoaphidis as a biocontrol agent.

Mutation and methylation analysis of TP53 in adrenal carcinogenesis

AIM

To investigate the role of coding region mutation and promoter hypermethylation of TP53 in adrenocortical cancer formation.

METHODS

Twenty sporadic adrenocortical cancers (ACCs) and five normal adrenal tissue samples were available for analysis. Coding region mutation of TP53 in 20 ACCs was examined by polymerase chain amplification using intronic primers for exons 2-11 and direct sequencing of the product. In 10 ACCs and five normal adrenal tissue specimens, methylation of the 16 CpG sites within the TP53 promoter was examined using bisulphite methylation sequencing.

RESULTS

Coding region mutation in TP53 was demonstrated in 5 of 20 ACCs. There were four mis-sense mutations and one frameshift mutation. Four of 5 patients with a TP53 mutation had metastases at diagnosis or detected soon thereafter and 3 of 4 died of disease within 12 months of surgical resection. No methylation was seen in the TP53 promoter in 10 ACC and the five normal adrenal tissues examined.

CONCLUSION

Coding region mutation in TP53 occurs in 25% of ACCs with a trend toward a poorer prognosis. Promoter methylation of TP53 is not present in ACC as a mechanism for tumour suppressor gene (TSG) inactivation and, therefore, other genes in the 17p13 region are implicated in adrenal carcinogenesis.

Ab initiodynamics study of poly-para-phenylene vinylene

We present an ab initio dynamics investigation within a density-functional perturbation theory framework of the properties of the conjugated polymer poly-para-phenylene vinylene (PPV) in both the isolated chain and crystalline states. The calculated results show that for an isolated chain, most of the vibrational modes correspond to experimentally observed modes in crystalline PPV. However, additional hitherto unidentified modes have been observed in experiment and our calculations on crystalline material have allowed us to assign these. We also present the results of calculations of the polarizability and permittivity tensors of the material, which are in reasonable agreement with the typical values for conjugated polymers. Dynamical Born effective charges [S. Baroni, S. de Gironcoli, A. Dal Corso, and P. Giannozzi, Rev. Mod. Phys. 73, 515 (2001)] are calculated and compared with atomic charges obtained from Mulliken population analysis [M. D. Segall, C. J. Pickard, R. Shah, and M. C. Payne, Mol. Phys. 89, 571 (1996)] and we conclude that effective charges are more appropriate for use in the study of the dynamics of the system. Notable differences are found in the infrared-absorption spectra obtained for the isolated chain and crystalline states, which can be attributed to the differences in the crystalline packing effects, which clearly play a key role in influencing the lattice dynamics of PPV.

Laboratory studies of the effects of reduced prey choice caused by Bt plants on a predatory insect

Crops transformed to express Bacillus thuringiensis (Bt) toxins can cause close to 100% mortality of certain target pest species. This study assessed the effect of target pest reduction on the predatory insect Chrysoperla carnea (Stephens) in the presence of alternative prey. Numbers of lacewings recovered from Bt oilseed rape (cultivar Oscar, event O52) did not differ significantly from numbers of lacewings recovered from conventional oilseed rape in cage experiments with the target pest Plutella xylostella (Linnaeus) and the non-target pest Myzus persicae (Sulzer) when aphid densities were high. However, significantly fewer lacewings were recovered from Bt plants as aphid densities were lowered. Lacewing weights were not affected by plant type.

Theoretical adlayer surface morphology of wurtzite 2 × 2 reconstructions of the GaN(0001) surface

In the first-principles calculations presented here we employ a density functional formalism using a pseudopotential plane-wave basis set in order to obtain the minimum energy configurations of various GaN(0001) 2 × 2 surfaces involving N atoms. The calculated formation energies of the 2 × 2 ideal model are compared with a previously proposed laterally contracted Ga bilayer model. We show how the order and stability of the different reconstructions are influenced by the choice of the standard 2 × 2 ideal or contracted bilayer model. On the basis of these results, we have characterized the effect on the adlayer surface of N segregation on the top of the surface, and the stability dependence on the number of substitutions for the different models employed. Our results predict that not all the adlayer structures containing nitrogen are unstable relative to the commonly considered N (H3) adatom configuration.

Dielectric and vibrational properties of amino acids

We calculate polarizability tensors and normal mode frequencies for the amino acids alanine, leucine, isoleucine, and valine using density functional perturbation theory implemented within the plane wave pseudopotential framework. It is found that the behavior of the electron density under external fields depends to a large extent on the geometrical structure of the molecule in question, rather than simply on the constituent functional groups. The normal modes are able to help distinguish between the different types of intramolecular hydrogen bonding present, and help to explain why leucine is found in the zwitterionic form for the gaseous phase. Calculated IR spectra show a marked difference between those obtained for zwitterionic and nonzwitterionic molecules. These differences can be attributed to the different chemical and hydrogen bonds present. Effective dynamical charges are calculated, and compared to atomic charges obtained from Mulliken population analysis. It is found that disagreement exists, largely due to the differing origins of these quantities.

Concentrations of cardiac troponin T in neonates with and without respiratory distress

AIMS

To establish a practical postnatal reference range for cardiac troponin T in neonates and to investigate concentrations in neonates with respiratory distress.

METHODS

Prospective investigation in a tertiary neonatal unit, recruiting infants with and without respiratory distress (sick and healthy infants respectively). Concentrations of cardiac troponin T were compared between sick and healthy infants, accounting for confounding variables.

RESULTS

A total of 162 neonates (113 healthy and 49 sick infants) had samples taken. The median (interquartile range) cardiac troponin T concentration in the healthy infants was 0.025 (0.01-0.062) ng/ml, and the 95th centile was 0.153 ng/ml. There were no significant relations between cardiac troponin T and various variables. The median (interquartile range) cardiac troponin T concentration in the sick infants was 0.159 (0.075-0.308) ng/ml. This was significantly higher (p < 0.0001) than in the healthy infants. In a linear regression model, the use of inotropes and oxygen requirement were significant associations independent of other basic and clinical variables in explaining the variation in cardiac troponin T concentrations.

CONCLUSIONS

Cardiac troponin T is detectable in the blood of many healthy neonates, but no relation with important basic and clinical variables was found. Sick infants have significantly higher concentrations than healthy infants. The variations in cardiac troponin T concentration were significantly associated with oxygen requirement or the use of inotropic support in a regression model. Cardiac troponin T may be a useful marker of neonatal and cardiorespiratory morbidity.

Evidence for gene flow and local clonal selection in field populations of the grain aphid (Sitobion avenae) in Britain revealed using microsatellites

Samples of the grain aphid, Sitobion avenae (F.), a major European pest of cereals, were collected in June and July 1997 from fields sown with winter wheat in a rough transect south-west of Rothamsted, UK. These aphids were genotyped at four microsatellite loci known from previous studies to be highly polymorphic. Allelic frequencies were similar between samples collected in the fields and in the 12.2 m high suction trap at Rothamsted, and there were many widespread genotypes (clones), providing evidence that the species is highly migratory. However, field samples were found to display a high level of genotypic heterogeneity (= variable clonal composition), most probably the result of clonal selection. The suction trap genotypes sample were slightly different from the field samples, indicative of the inclusion of genotypes from plant hosts (cereals and grasses, Poaceae) other than winter wheat and/or genotype-biased emigration from the field. The relevance of these data to modelling of aphid outbreaks is briefly discussed.

Ban on triazine herbicides likely to reduce but not negate relative benefits of GMHT maize cropping

The UK Farm-Scale Evaluations (FSE) compared the effects on biodiversity of management of genetically modified herbicide-tolerant (GMHT) spring-sown crops with conventional crop management. The FSE reported larger weed abundance under GMHT management for fodder maize, one of three crops studied. Increased seed production may be important for the long-term persistence of these arable weeds and may benefit invertebrates, small mammals and seed-eating birds. In three-quarters of FSE maize fields, growers used atrazine on the conventionally managed half, reflecting contemporary commercial practice. Withdrawal of the triazine herbicides atrazine, simazine and cyanazine from approved lists of EU chemicals could therefore reduce or even reverse the reported benefits of GMHT maize. Here we analyse effects of applications of triazine herbicides in conventional maize regimes on key indicators, using FSE data. Weed abundances were decreased greatly relative to all other regimes whenever atrazine was applied before weeds emerged. Here, we forecast weed abundances in post-triazine herbicide regimes. We predict weed abundances under future conventional herbicide management to be considerably larger than that for atrazine used before weeds emerged, but still smaller than for the four FSE sites analysed that used only non-triazine herbicides. Our overall conclusion is that the comparative benefits for arable biodiversity of GMHT maize cropping would be reduced, but not eliminated, by the withdrawal of triazines from conventional maize cropping.

Right ventricular volume measurements in ventilated preterm neonates

Pulmonary hypertension is associated with worse perinatal outcomes in infants with respiratory disorders. In these infants, right ventricular dysfunction may result in poor pulmonary blood flow. The objective of this study was to follow changes in right ventricular volumes during the first 2 days of life in infants with respiratory distress syndrome. Serial echocardiographic examinations were performed on days 0-2 on infants ventilated for respiratory distress syndrome. Two-dimensional echocardiography with the ellipsoid approximation was used to calculate systolic and diastolic volumes. In 17 ventilated preterm infants, right ventricular volumes were significantly lower on day 2 compared with day 0 and decreased from a median (interquartile range) end systolic volume of 0.80 ml/kg (0.66-0.91 ml/kg) to 0.45 ml/kg (0.39-0.54 ml/kg) ( p < 0.001). End diastolic volume decreased from a median (interquartile range) of 1.54 ml/kg (1.44-1.65 ml/kg) to 1.30 ml/kg (1.22-1.60 ml/kg) ( p = 0.039). Right ventricular ejection fraction increased from a median (interquartile range) of 0.48 ml/kg (0.44-0.56 ml/kg) to 0.62 ml/kg (0.58-0.71 ml/kg) during the same period ( p < 0.001), as did right ventricular output from a median (interquartile range) 120 ml/kg/min (96-125 ml/kg/min) to 140 ml/kg/min (113-168 ml/kg/min) ( p = 0.044). Right ventricular volume decreases during the first 2 days of life in ventilated preterm infants. However, right ventricular performance is maintained.

Weeds in fields with contrasting conventional and genetically modified herbicide-tolerant crops. I. Effects on abundance and diversity

We compared the seedbanks, seed rains, plant densities and biomasses of weeds under two contrasting systems of management in beet, maize and spring oilseed rape. Weed seedbank and plant density were measured at the same locations in two subsequent seasons. About 60 fields were sown with each crop. Each field was split, one half being sown with a conventional variety managed according to the farmer's normal practice, the other half being sown with a genetically modified herbicide-tolerant (GMHT) variety, with weeds controlled by a broad-spectrum herbicide. In beet and rape, plant densities shortly after sowing were higher in the GMHT treatment. Following weed control in conventional beet, plant densities were approximately one-fifth of those in GMHT beet. In both beet and rape, this effect was reversed after the first application of broad-spectrum herbicide, so that late-season plant densities were lower in the GMHT treatments. Biomass and seed rain in GMHT crops were between one-third and one-sixth of those in conventional treatments. The effects of differing weed-seed returns in these two crops persisted in the seedbank: densities following the GMHT treatment were about 20% lower than those following the conventional treatment. The effect of growing maize was quite different. Weed density was higher throughout the season in the GMHT treatment. Late-season biomass was 82% higher and seed rain was 87% higher than in the conventional treatment. The difference was not subsequently detectable in the seedbank because the total seed return was low after both treatments. In all three crops, weed diversity was little affected by the treatment, except for transient effects immediately following herbicide application.

Weeds in fields with contrasting conventional and genetically modified herbicide-tolerant crops. II. Effects on individual species

We compared the effects of the management of genetically modified herbicide-tolerant (GMHT) and conventional beet, maize and spring oilseed rape on 12 weed species. We sampled the seedbank before and after cropping. During the season we counted plants and measured seed rain and biomass. Ratios of densities were used to calculate emergence, survival, reproduction and seedbank change. Treatments significantly affected the biomass of six species in beet, eight in maize and five in spring oilseed rape. The effects were generally consistent, with biomass lower in GMHT beet and spring oilseed rape and higher in GMHT maize. With few exceptions, emergence was higher in GMHT crops. Subsequent survival was significantly lowered for eight species in beet and six in spring oilseed rape in the GMHT treatments. It was increased for five species in maize and one in spring oilseed rape. Significant effects on seedbank change were found for four species. However, for many species in beet and spring oilseed rape (19 out of 24 cases), seed densities were lower in the seedbank after GMHT cropping. These differences compounded over time would result in large decreases in population densities of arable weeds. In maize, populations may increase.

Invertebrate responses to the management of genetically modified herbicide-tolerant and conventional spring crops. II. Within-field epigeal and aerial arthropods

The effects of the management of genetically modified herbicide-tolerant (GMHT) crops on the abundances of aerial and epigeal arthropods were assessed in 66 beet, 68 maize and 67 spring oilseed rape sites as part of the Farm Scale Evaluations of GMHT crops. Most higher taxa were insensitive to differences between GMHT and conventional weed management, but significant effects were found on the abundance of at least one group within each taxon studied. Numbers of butterflies in beet and spring oilseed rape and of Heteroptera and bees in beet were smaller under the relevant GMHT crop management, whereas the abundance of Collembola was consistently greater in all GMHT crops. Generally, these effects were specific to each crop type, reflected the phenology and ecology of the arthropod taxa, were indirect and related to herbicide management. These results apply generally to agriculture across Britain, and could be used in mathematical models to predict the possible long-term effects of the widespread adoption of GMHT technology. The results for bees and butterflies relate to foraging preferences and might or might not translate into effects on population densities, depending on whether adoption leads to forage reductions over large areas. These species, and the detritivore Collembola, may be useful indicator species for future studies of GMHT management.