Order-disorder and ionic conductivity in calcium nitride-hydride.

Recently nitrogen-hydrogen compounds have successfully been applied as co-catalysts for mild conditions ammonia synthesis. Ca2NH was shown to act as a H2 sink during reaction, with H atoms from its lattice being incorporated into the NH3(g) product. Thus the ionic transport and diffusion properties of the N-H co-catalyst are fundamentally important to understanding and developing such syntheses. Here we show hydride ion conduction in these materials. Two distinct calcium nitride-hydride Ca2NH phases, prepared via different synthetic paths are found to show dramatically different properties. One phase (ß) shows fast hydride ionic conduction properties (0.08 S/cm at 600 °C), on a par with the best binary ionic hydrides and 10 times higher than CaH2, whilst the other (α) is 100 times less conductive. An in situ combined analysis techniques reveals that the effective ß-phase conducts ions via a vacancy-mediated phenomenon in which the charge carrier concentration is dependent on the ion concentration in the secondary site and by extension the vacancy concentration in the main site.

Retrospective application of the HEAR score on patients evacuated for chest pain: Assessing the utility of point-of-care troponin.

INTRODUCTION: The HEART scoring system codifies the clinical gestalt used by physicians with 0-2 points assigned to 5 criteria (history, electrocardiography, age, risk factors and troponin). This scoring provides a prognostic tool that assists in disposition planning. The use of a truncated HEART score, minus the troponin data (HEAR score), was used for patients presenting with chest pain at one of four outpost nursing stations served by La Ronge Health Centre in northern Saskatchewan. These nursing stations have no onsite physician and no ability to obtain any troponin data. This study set out to determine if there was any utility in conducting point-of-care (PoC) troponins in these nursing outposts. MATERIALS AND METHODS: A retrospective analysis was conducted using the La Ronge regional electronic medical record by searching for all patients for whom an outpost nurse had called a physician regarding chest pain symptoms between 01 January 2011 and 31 December 2016. The HEAR and HEART score were then calculated for each individual presentation of patients with chest pain that met inclusion and exclusion criteria. RESULTS: By calculating both the patient's HEART score before evacuation from the outposts and after (i.e. with the troponin data), we were able to determine that, in 89.4% of cases (110/123 events), patients would require evacuation regardless of the troponin values due to a HEART score ≥4. In 10.6% (13/124 events) of cases, the patients who were evacuated had a HEART score ≤3, and in only one case did the troponin data increase this score. CONCLUSIONS: The majority of patients would continue to be evacuated regardless of the result of their PoC troponin due to an already elevated HEAR score. PoC troponin is unlikely to reduce the rate of evacuation of patients with chest pain from the nursing stations served by the La Ronge Health Centre.

Résumé Introduction: Le système de pointage HEART codifie la gestalt clinique utilisée par les médecins avec 0­2 points attribués à 5 critères (anamnèse, ECG, âge, facteurs de risque, troponine). Ce pointage est un outil pronostique qui aide à planifier les soins aux patients. Un score HEART tronqué, c'est-à-dire moins les données de troponine (score HEAR), a été utilisé chez les patients qui se présentaient pour douleur thoracique à 1 des 4 avant-postes de soins infirmiers servis par le centre La Ronge Health Centre au nord de la Saskatchewan. Il n'y a pas de médecin sur place à ces postes de soins infirmiers, et il est impossible d'obtenir des données sur la troponine. Cette étude voulait déterminer si le dosage ciblé de troponine est utile dans ces avant-postes de soins infirmiers. Méthodes: Une analyse rétrospective a été réalisée à l'aide du dossier médical électronique de la région de La Ronge après une recherche de tous les patients pour lesquels un avant-poste de soins infirmiers avait appelé un médecin pour des symptômes de douleur thoracique entre le 1er Janvier 2011 et le 31 Décembre 2016. Les scores HEAR et HEART ont alors été calculés pour chaque cas de douleur thoracique qui répondait aux critères d'inclusion et d'exclusion. Résultats: En calculant le score HEART (c.-à-d. avec les données sur la troponine) avant et après l'évacuation du patient de l'avant-poste, nous avons pu déterminer que dans 89,4% des cas (110/123 événements), les patients devraient être évacués sans égard aux valeurs de troponine en raison d'un score HEART ≤3 et la troponine a augmenté ce score dans un seul cas. Conclusions: La majorité des patients continueraient d'être évacués, peu importe les résultats de troponine ciblée en raison d'un score HEAR déjà élevé. La troponine ciblée ne réduirait probablement pas le taux d'évacuation des patients pour douleur thoracique des postes de soins infirmiers servis par le centre La Ronge Health Centre. Mots-clés: Maladie cardiaque, médecine rurale, score HEART, troponine.

Toward an all-inclusive trauma system in Central South Ontario: development of the Trauma-System Performance Improvement and Knowledge Exchange (T-SPIKE) project.

Background: There is currently no integrated data system to capture the true burden of injury and its management within Ontario's regional trauma networks (RTNs), largely owing to difficulties in identifying these patients across the multiple health care provider records. Our project represents an iterative effort to create the ability to chart the course of care for all injured patients within the Central South RTN. Methods: Through broad stakeholder engagement of major health care provider organizations within the Central South RTN, we obtained research ethics board approval and established data-sharing agreements with multiple agencies. We tested identification of trauma cases from Jan. 1 to Dec. 31, 2017, and methods to link patient records between the various echelons of care to identify barriers to linkage and opportunities for administrative solutions. Results: During 2017, potential trauma cases were identified within ground paramedic services (23 107 records), air medical transport services (196 records), referring hospitals (7194 records) and the lead trauma hospital trauma registry (1134 records). Linkage rates for medical records between services ranged from 49% to 92%. Conclusion: We successfully conceptualized and provided a preliminary demonstration of an initiative to collect, collate and accurately link primary data from acute trauma care providers for certain patients injured within the Central South RTN. Administration-level changes to the capture and management of trauma data represent the greatest opportunity for improvement.

Contexte: On ne dispose actuellement d'aucun système intégré de gestion des données pour évaluer le fardeau réel des traumatismes et de leur gestion dans les réseaux régionaux de traumatologie (RRT) en Ontario, en bonne partie en raison de la difficulté d'identifier les cas parmi la multiplicité des dossiers d'intervenants médicaux. Notre projet représente un effort itératif pour créer la capacité de cartographier le parcours de soin de tous les polytraumatisés du RRT de la région Centre-Sud. Méthodes: Grâce à l'engagement général des intervenants des grandes organisations de santé du RRT de la région Centre-Sud, nous avons obtenu l'approbation d'un comité d'éthique de la recherche et conclu des accords de partage des données avec plusieurs agences. Nous avons testé l'identification des cas de traumatologie du 1er janvier au 31 décembre 2017 et les méthodes de liaison des dossiers de patients entre les divers échelons de soin pour identifier les obstacles à la liaison et leurs solutions administratives possibles. Résultats: Au cours de 2017, les cas de traumatologie potentiels ont été identifiés auprès des services ambulanciers terrestres (23 107 dossiers), des services de transport médical aérien (196 dossiers), des hôpitaux référents (7194 dossiers) et du registre hospitalier principal de traumatologie (1134 dossiers). Les taux de liaison entre les différents services pour les dossiers médicaux variaient de 49 % à 92 %. Conclusion: Nous avons conceptualisé et présenté avec succès la démonstration préliminaire d'un projet visant à recueillir, colliger et relier avec justesse les données primaires des intervenants en traumatologie aiguë pour certains patients blessés du RRT du Centre-Sud. Des changements administratifs centrés sur la saisie et la gestion des données de traumatologie représentent la meilleure voie vers une amélioration.

Photo-catalytic hydrogen production over Au/g-C3N4: effect of gold particle dispersion and morphology.

Metal/semiconductor interactions affect electron transfer rates and this is central to photocatalytic hydrogen ion reduction. While this interaction has been studied in great detail on metal oxide semiconductors, not much is known of Au particles on top of polymeric semiconductors. The effects of gold nanoparticle size and dispersion on top of g-C3N4 were studied by core and valence level spectroscopy and transmission electron microscopy in addition to catalytic tests. The as-prepared, non-calcined catalysts displayed Au particles with uniform dimension (mean particle size = 1.8 nm) and multiple electronic states: XPS Au 4f7/2 lines at 84.9 and 87.1 eV (each with a spin-orbit splitting of 3.6-3.7 eV). These particles, which did not show localized surface plasmon resonance (LSPR), before the reaction, doubled in size after the reaction giving a pronounced LSPR at about 550 nm. The effect of the heating environment on these particles (in air or in H2) was further investigated. While heating in H2 gave Au nanoparticles of different shapes, heating under O2 gave exclusively spherical particles. Similar activity towards photocatalytic hydrogen ion reduction under UV excitation was seen in both cases, however. XPS Au 4f analyses indicated that an increase in deposition time, during catalyst preparation, resulted in an increase in the initial fraction of oxidized gold particles, which were easily reduced under hydrogen. The valence band region for Au/gC3N4 was further studied in an effort to compare it to what is already known for Au/metal oxide semiconductors. A shift of over 2 eV for the Au 5d doublets was noticed between reduced and oxidized gold particles with mean particle sizes between 2 and 6 nm, which is consistent with the final state effect. A narrow range of gold loading for optimal catalytic performance was seen, where it seems that a density of one Au particle per 10 × 10 nm2 is the most suitable. Particle size and shape had a minor effect on performance, which may indicate the absence of a plasmonic effect on the reaction rate.

PTSD in women is associated with a block in conversion of progesterone to the GABAergic neurosteroids allopregnanolone and pregnanolone measured in plasma.

There is a need to identify new and more effective treatments for posttraumatic stress disorder (PTSD). Allopregnanolone and its stereoisomer pregnanolone (together termed ALLO) are metabolites of progesterone that positively and allosterically modulate GABA effects at GABAA receptors, thereby reducing anxiety and depression. Previous research revealed that women with PTSD had low cerebrospinal fluid (CSF) ALLO levels and a low ratio of ALLO to the allopregnanolone precursor 5α-DHP, consistent with deficient activity of the ALLO synthetic enzyme 3α-hydroxysteroid dehydrogenase (3α-HSD). The current study examined ALLO and the ratio of ALLO to 5α-DHP in plasma at rest and in response to psychophysiological stressors in trauma-exposed, medication-free women with and without PTSD. Participants were examined twice in random order during the early follicular phase (eFP) and mid-luteal phase (mLP) of the menstrual cycle. Plasma neurosteroids were measured using gas chromatography-mass spectrometry. Results indicate that the ALLO to 5α-DHP ratio in plasma increases between the eFP and mLP. In addition, women with PTSD have a lower ratio of ALLO to 5α-DHP than trauma-exposed healthy women, as well as blunted increases in this ratio in response to a moderately stressful laboratory procedure, i.e., differential fear conditioning, across the menstrual cycle. Clinically feasible testing for 3α-HSD dysfunction is critical to translating this line of research into clinical care. Measurement of this ratio in plasma could facilitate patient stratification in clinical treatment trials, as well as precision medicine targeting of treatments that address ALLO synthesis deficits in women with PTSD.

A perspective on liquid salts for energy and materials.

Liquid salts comprising molten salts and ionic liquids offer important media to address both energy and materials challenges. Here we review topics presented in this Faraday Discussion volume related to improved electrowinning of metals, optimisation of processes, new electrochemical device concepts, chemistry in ionic liquids, conversion of biomass, carbon chemistry and nuclear applications. The underlying phenomenology is then reviewed and commentary given. Some future applications are then discussed, further exemplifying the high potential rewards achievable from these chemistries.

Probing the energy levels of perovskite solar cells via Kelvin probe and UV ambient pressure photoemission spectroscopy.

The field of organo-lead halide perovskite solar cells has been rapidly growing since their discovery in 2009. State of the art devices are now achieving efficiencies comparable to much older technologies like silicon, while utilising simple manufacturing processes and starting materials. A key parameter to consider when optimising solar cell devices or when designing new materials is the position and effects of the energy levels in the materials. We present here a comprehensive study of the energy levels present in a common structure of perovskite solar cell using an advanced macroscopic Kelvin probe and UV air photoemission setup. By constructing a detailed map of the energy levels in the system we are able to predict the importance of each layer to the open circuit voltage of the solar cell, which we then back up through measurements of the surface photovoltage of the cell under white illumination. Our results demonstrate the effectiveness of air photoemission and Kelvin probe contact potential difference measurements as a method of identifying the factors contributing to the open circuit voltage in a solar cell, as well as being an excellent way of probing the physics of new materials.

Energy band diagram of device-grade silicon nanocrystals.

Device grade silicon nanocrystals (NCs) are synthesized using an atmospheric-pressure plasma technique. The Si NCs have a small and well defined size of about 2.3 nm. The synthesis system allows for the direct creation of thin films, enabling a range of measurements to be performed and easy implementation of this material in different devices. The chemical stability of the Si NCs is evaluated, showing relatively long-term durability thanks to hydrogen surface terminations. Optical and electrical characterization techniques, including Kelvin probe, ultraviolet photoemission spectroscopy and Mott-Schottky analysis, are employed to determine the energy band diagram of the Si NCs.

The effect of Pt NPs crystallinity and distribution on the photocatalytic activity of Pt-g-C3N4.

Loading of a co-catalyst on the surface of a semiconductor photocatalyst is often carried out without considering the effect of the loading procedure on the final product. The present study looks in detail at the effect that the loading method has on the morphology and final composition of platinum-based nanoparticles by means of XPS and TEM analysis. Additionally, reduction pre-treatments are performed to investigate how the coverage, crystallinity and composition of the NPs affect the photocatalytic H2 evolution. The activity of Pt-g-C3N4 can significantly be enhanced by controlling the properties of the co-catalyst NPs.

A comparison of risk factors associated with community-associated methicillin-resistant and -susceptible Staphylococcus aureus infections in remote communities.

In this case-control study, cases [community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), n=79] and controls [community-associated methicillin-susceptible S. aureus (CA-MSSA), n=36] were defined as a laboratory-confirmed infection in a patient with no previous hospital-associated factors. Skin and soft tissue were the predominant sites of infection, both for cases (67.1%) and controls (55.6%). Most of the cases (79.7%) and controls (77.8%) were aged <30 years. Investigations did not reveal any significant statistical differences in acquiring a CA-MRSA or CA-MSSA infection. The most common shared risk factors included overcrowding, previous antibiotic usage, existing skin conditions, household exposure to someone with a skin condition, scratches/insect bites, and exposure to healthcare workers. Similar risk factors, identified for both CA-MRSA and CA-MSSA infections, suggest standard hygienic measures and proper treatment guidelines would be beneficial in controlling both CA-MRSA and CA-MSSA in remote communities.

Plasticity in hydraulic architecture of Scots pine across Eurasia.

Widespread tree species must show physiological and structural plasticity to deal with contrasting water balance conditions. To investigate these plasticity mechanisms, a meta-analysis of Pinus sylvestris L. sap flow and its response to environmental variables was conducted using datasets from across its whole geographical range. For each site, a Jarvis-type, multiplicative model was used to fit the relationship between sap flow and photosynthetically active radiation, vapour pressure deficit (D) and soil moisture deficit (SMD); and a logarithmic function was used to characterize the response of stomatal conductance (G(s)) to D. The fitted parameters of those models were regressed against climatic variables to study the acclimation of Scots pine to dry/warm conditions. The absolute value of sap flow and its sensitivity to D and SMD increased with the average summer evaporative demand. However, relative sensitivity of G(s) to D (m/G (s,ref), where m is the slope and G(s,ref) is reference G(s) at D = 1 kPa) did not increase with evaporative demand across populations, and transpiration per unit leaf area at a given D increased accordingly in drier/warmer climates. This physiological plasticity was linked to the previously reported climate- and size-related structural acclimation of leaf to sapwood area ratios. G (s,ref), and its absolute sensitivity to D(m), tended to decrease with age/height of the trees as previously reported for other pine species. It is unclear why Scots pines have higher transpiration rates at drier/warmer sites, at the expense of lower water-use efficiency. In any case, our results suggest that these structural adjustments may not be enough to prevent lower xylem tensions at the driest sites.

Age-related changes in ecosystem structure and function and effects on water and carbon exchange in ponderosa pine.

As forests age, their structure and productivity change, yet in some cases, annual rates of water loss remain unchanged. To identify mechanisms that might explain such observations, and to determine if widely different age classes of forests differ functionally, we examined young (Y, approximately 25 years), mature (M, approximately 90 years) and old (O, approximately 250 years) ponderosa pine (Pinus ponderosa Dougl. ex P. Laws.) stands growing in a drought-prone region of central Oregon. Although the stands differed in tree leaf area index (LAIT) (Y = 0.9, M = 2.8, O = 2.1), cumulative tree transpiration measured by sap flow did not differ substantially during the growing season (100-112 mm). Yet when water was readily available, transpiration per unit leaf area of the youngest trees was about three times that of M trees and five times that of O trees. These patterns resulted from a nearly sixfold difference in leaf specific conductance (KL) between the youngest and oldest trees. At the time of maximum transpiration in the Y stand in May-June, gross carbon uptake (gross ecosystem production, GEP) was similar for Y and O stands despite an almost twofold difference in stand leaf area index (LAIS). However, the higher rate of water use by Y trees was not sustainable in the drought-prone environment, and between spring and late summer, KL of Y trees declined fivefold compared with a nearly twofold decline for M trees and a < 30% reduction in O trees. Because the Y stand contained a significant shrub understory and more exposed soil, there was no appreciable difference in mean daily latent energy fluxes between the Y stand and the older stands as measured by the eddy-covariance technique. These patterns resulted in 60 to 85% higher seasonal GEP and 55 to 65% higher water-use efficiency at the M and O stands compared with the Y stand.

Advanced anodes for high-temperature fuel cells.

Fuel cells will undoubtedly find widespread use in this new millennium in the conversion of chemical to electrical energy, as they offer very high efficiencies and have unique scalability in electricity-generation applications. The solid-oxide fuel cell (SOFC) is one of the most exciting of these energy technologies; it is an all-ceramic device that operates at temperatures in the range 500-1,000 degrees C. The SOFC offers certain advantages over lower temperature fuel cells, notably its ability to use carbon monoxide as a fuel rather than being poisoned by it, and the availability of high-grade exhaust heat for combined heat and power, or combined cycle gas-turbine applications. Although cost is clearly the most important barrier to widespread SOFC implementation, perhaps the most important technical barriers currently being addressed relate to the electrodes, particularly the fuel electrode or anode. In terms of mitigating global warming, the ability of the SOFC to use commonly available fuels at high efficiency, promises an effective and early reduction in carbon dioxide emissions, and hence is one of the lead new technologies for improving the environment. Here, we discuss recent developments of SOFC fuel electrodes that will enable the better use of readily available fuels.

An EST survey of the sugarcane transcriptome.

Its large genome and high polyploidy makes sugarcane (Saccharum spp.) a singularly challenging crop to study and improve using genetic approaches. To provide large numbers of functionally characterized candidate genes that might be tested for direct association (rather than distant linkage) with economically important traits, we sequenced the 5' ends of 9,216 clones from three cDNA libraries (apex, leaf and mature internode), representing 3,401 non-redundant sequences. About 57% of these sequences could be assigned a tentative function based on statistically significant similarity to previously characterized proteins or DNA sequences. Another 28% corresponded to previously identified, but uncharacterized, sequences. Some of the remaining unidentified sequences were predicted to be genes which could potentially be new to plants or unique to sugarcane. Comparisons of the sugarcane ESTs to a large sorghum EST database revealed similar compositions of expressed genes between some different tissues. Comparison to a detailed Arabidopsis protein database showed some highly conserved sequences, which might be useful DNA markers for pan-angiosperm comparative mapping. These EST sequences provide a foundation for many new studies to accelerate isolation of agronomically important genes from the cumbersome sugarcane genome.

Relaxation to bradykinin in bovine pulmonary supernumerary arteries can be mediated by both a nitric oxide-dependent and -independent mechanism.

1. The aim of the present study was to determine the relative contribution of prostanoids, nitric oxide and K(+) channels in the bradykinin-induced relaxation of bovine pulmonary supernumerary arteries. 2. In endothelium-intact, but not denuded rings, bradykinin produced a concentration-dependent relaxation (pEC(50), 9.6+/-0.1), which was unaffected by the cyclo-oxygenase inhibitor indomethacin. The nitric oxide scavenger hydroxocobalamin (200 micro M, pEC(50), 8.5+/-0.2) and the nitric oxide synthase inhibitor L-NAME (100 micro M, pEC(50), 8.9+/-0.1) and the combination of L-NAME and hydroxocobalamin (pEC(50), 8.1+/-0.2) produced rightward shifts in the bradykinin concentration response curve. 3. The guanylyl cyclase inhibitor ODQ (10 micro M, pEC(50), 9.6+/-0.4) did not affect the response to bradykinin. 4. Elevating the extracellular [K(+)] to 30 mM did not affect the response to bradykinin but abolished the response when ODQ or L-NAME was present. 5. The K(+) channel blocker apamin (100 nM), combined with charybdotoxin (100 nM), produced a small reduction in the maximum response to bradykinin but they abolished the response to bradykinin when ODQ, L-NAME or hydroxocobalamin were present. Apamin (100 nM) combined with iberiotoxin (100 nM) also reduced the response to bradykinin in the presence of hydroxocobalamin or L-NAME. 6. The concentration response curve for sodium nitroprusside-induced relaxation was abolished by ODQ (10 micro M) and shifted to the right by apamin and charybdotoxin. 7. These studies suggest that in bovine pulmonary supernumerary arteries bradykinin can stimulate the formation of nitric oxide and activate an EDHF-like mechanism and that either of these pathways alone can mediate the bradykinin-induced relaxation. In addition nitric oxide, acting through guanylyl cyclase, can activate an apamin/charbydotoxin-sensitive K(+) channel in this tissue.

Canopy stomatal conductance and xylem sap abscisic acid (ABA) in mature Scots pine during a gradually imposed drought.

We investigated the effect of drought on canopy stomatal conductance (g(c)), and examined the hypothesis that g(c) is controlled by the chemical messenger abscisic acid (ABA) produced in roots. Beginning in November 1994, we subjected a mature stand of Scots pine (Pinus sylvestris L.) to an imposed 11-month drought. Control plots were maintained at average-season soil water content. Xylem sap was extracted from shoots at regular intervals from April to November 1995. Soil water, sap flow and leaf water potentials (predawn to dusk) were recorded at the same time. Canopy stomatal conductance was calculated from sap flow data and xylem sap ABA concentrations ([ABA(xyl)]) were measured by radioimmunoassay. Mean [ABA(xyl)] in control trees was 250 micromol m(-3). No diurnal variation in [ABA(xyl)] was detected. With soil drying, [ABA(xyl)] increased to a maximum in summer (600 micromol m(-3)), but decreased again toward autumn; however, no significant increase in ABA flux to the leaves occurred. A decline in g(c) was detected when volumetric soil water content declined below 0.12. The decline in g(c) could not have been mediated by increasing [ABA(xyl)] because stomatal closure appeared to precede any increase in [ABA(xyl)]. Peak sap flow velocity data were used to estimate delivery times for root-to-shoot signals in 15-m tall trees. Under normal field conditions, a signal would take 12 days to travel from the site of production (roots) to the presumed site of action (shoots). However, under drought conditions it may take a chemical signal in excess of 6 weeks. We conclude that a feedforward model of short-term stomatal response to soil drying, based solely on the action of a chemical messenger from the roots, is not applicable in mature conifer trees because signal transmission is too slow.

Water limitations to carbon exchange in old-growth and young ponderosa pine stands.

We investigated the impact of seasonal soil water deficit on the processes driving net ecosystem exchange of carbon (NEE) in old-growth and recently regenerating ponderosa pine (Pinus ponderosa Doug. ex Laws.) stands in Oregon. We measured seasonal patterns of transpiration, canopy conductance and NEE, as well as soil water, soil temperature and soil respiration. The old-growth stand (O) included two primary age classes (50 and 250 years), had a leaf area index (LAI) of 2.1 and had never been logged. The recently regenerating stand (Y) consisted predominantly of 14-year-old ponderosa pine with an LAI of 1.0. Both stands experienced similar meteorological conditions with moderately cold wet winters and hot dry summers. By August, soil volumetric water content within the upper 30 cm had declined to a seasonal minimum of 0.07 at both sites. Between April and June, both stands showed similar rates of transpiration peaking at 0.96 mm day(-1); thereafter, trees at the Y site showed increasing drought stress with canopy stomatal resistance increasing 6-fold by mid-August relative to values for trees at the O site. Over the same period, predawn water potential (psi(pd)) of trees at the Y site declined from -0.54 to -1.24 MPa, whereas psi(pd) of trees at the O site remained greater than -0.8 MPa throughout the season. Soil respiration at the O site showed a strong seasonal correlation with soil temperature with no discernible constraints imposed by declining soil water. In contrast, soil respiration at the Y site peaked before seasonal maximal soil temperatures and declined thereafter with declining soil water. No pronounced seasonal pattern in daytime NEE was observed at either site between April and September. At the Y site this behavior was driven by concurrent soil water limitations on soil respiration and assimilation, whereas there was no evidence of seasonal soil water limitations on either process at the O site.

Psychological adjustment to familial-genetic risk assessment for ovarian cancer: predictors of nonadherence to surveillance recommendations.

OBJECTIVE: To evaluate whether self-report measures of psychological distress and perceived risk were associated with nonadherence to recommended ovarian cancer surveillance. METHODS: Eighty-three patients attending the Familial Ovarian Cancer Clinic (FOCC) at Princess Margaret Hospital were assessed psychosocially prior to and during initial familial-genetic assessment and then monitored for adherence with recommended follow-up surveillance over a period of 12-18 months. The assessment protocol included an investigator-designed clinic questionnaire, the State-Trait Anxiety Inventory (STAI), Center for Epidemiologic Studies Depression Scale (CESD), Life Orientation Test (LOT), Medical Outcomes Study Social Support Survey (MOSSS), Texas Inventory of Grief, and the COPE. Nonadherence was measured in terms of unexplained absences at one or two recommended and scheduled surveillance appointments following the familial-genetic assessment. RESULTS: Univariate tests revealed a significant association between higher perception of ovarian cancer risk, as assessed immediately after the familial-genetic risk assessment in the clinic and nonadherence to physician-recommended surveillance (chi2 (2, N = 83) = 9.75, P < 0.008). Empirically based estimates of risk, conveyed by the clinic team to subjects, were not significantly associated with nonadherence (chi2 (2, N = 83) = 0.19, P = 0.91). Logistic regression analysis revealed that subjects who perceived themselves to be at high ovarian cancer risk were five times more likely to be nonadherent than participants who perceived themselves to be at low or medium ovarian cancer risk. CONCLUSIONS: These results suggest that higher self-perceived risk may predict adherence difficulties to recommended surveillance in women attending a familial-genetic risk clinic.

QTL analysis in a complex autopolyploid: genetic control of sugar content in sugarcane.

QTL mapping in autopolyploids is complicated by the possibility of segregation for three or more alleles at a locus and by a lack of preferential pairing, however the subset of polymorphic alleles that show simplex segregation ratios can be used to locate QTLs. In autopolyploid Saccharum, 36 significant associations between variation in sugar content and unlinked loci detected by 31 different probes were found in two interspecific F(1) populations. Most QTL alleles showed phenotypic effects consistent with the parental phenotypes, but occasional transgressive QTLs revealed opportunities to purge unfavorable alleles from cultivars or introgress valuable alleles from exotics. Several QTLs on homologous chromosomes appeared to correspond to one another-multiple doses of favorable 'alleles' at such chromosomal region(s) yielded diminishing returns-such negative epistasis may contribute to phenotypic buffering. Fewer sugar content QTLs were discovered from the highest-sugar genotype than from lower-sugar genotypes, perhaps suggesting that many favorable alleles have been fixed by prior selection, i.e. that the genes for which allelic variants (QTLs) persist in improved sugarcanes may be a biased subset of the population of genes controlling sugar content. Comparison of these data to mutations and QTLs previously mapped in maize hinted that seed and biomass crops may share a partly-overlapping basis for genetic variation in carbohydrate deposition. However, many QTLs do not correspond to known candidate genes, suggesting that other approaches will be necessary to isolate the genetic determinants of high sugar content of vegetative tissues.