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The transport of dissolved organic matter (DOM) across the land-ocean-aquatic-continuum (LOAC), from freshwater to the ocean, is an important yet poorly understood component of the global carbon budget. Exploring and quantifying this flux is a significant challenge given the complexities of DOM cycling across these contrasting environments. We developed a new model, UniDOM, that unifies concepts, state variables and parameterisations of DOM turnover across the LOAC. Terrigenous DOM is divided into two pools, T1 (strongly-UV-absorbing) and T2 (non- or weakly-UV-absorbing), that exhibit contrasting responses to microbial consumption, photooxidation and flocculation. Data are presented to show that these pools are amenable to routine measurement based on specific UV absorbance (SUVA). In addition, an autochtonous DOM pool is defined to account for aquatic DOM production. A novel aspect of UniDOM is that rates of photooxidation and microbial turnover are parameterised as an inverse function of DOM age. Model results, which indicate that ~ 5% of the DOM originating in streams may penetrate into the open ocean, are sensitive to this parameterisation, as well as rates assigned to turnover of freshly-produced DOM. The predicted contribution of flocculation to DOM turnover is remarkably low, although a mechanistic representation of this process in UniDOM was considered unachievable because of the complexities involved. Our work highlights the need for ongoing research into the mechanistic understanding and rates of photooxidation, microbial consumption and flocculation of DOM across the different environments of the LOAC, along with the development of models based on unified concepts and parameterisations. [ABSTRACT FROM AUTHOR]

The main objective of this work is to predict the mixing of two different miscible oils in a very long channel. The background to this problem relates to the mixing of heavy and light oil in a pipeline. As a first step, a 2D channel with an aspect ratio of 250 is considered. The batch-mixing of two miscible crude oils with different viscosities and densities is modeled using an unsteady laminar model and unsteady RANS model available in the commercial CFD solver ANSYS-Fluent. For a comparison, a LES model was used for a 3D version of the 2D channel. The distinguishing feature of this work is the Lagrangian coordinate system utilized to set no-slip wall boundary conditions. The global CFD model has been validated against classical analytical solutions. Excellent agreement has been achieved. Simulations were carried out for a Reynolds number of 6300 (calculated using light oil properties) and a Schmidt number of 104. The results show that, in contrast to the unsteady RANS model, the LES and unsteady laminar models produce comparable mixing dynamics for two oils in the channel. Analysis of simulations also shows that, for a channel length of 100 m and a height of 0.4 m, the complete mixing of two oils across the channel has not been achieved. We showed that the mixing zone consists of the three different mixing sub-zones, which have been identified using the averaged mass fraction of the heavy oil along the flow direction. The first sub-zone corresponds to the main front propagation area with a length of several heights of the channel. The second and third sub-zones are characterized by so-called shear-flow-driven mixing due to the Kelvin-Helmholtz vortices occurring between oils in the axial direction. It was observed that the third sub-zone has a steeper mass fraction gradient of the heavy oil in the axial direction in comparison with the second sub-zone, which corresponds to the flow-averaged mass fraction of 0.5 for the heavy oil. [ABSTRACT FROM AUTHOR]

Antarctic krill ( Euphausia superba) play a central role in the food web of the Southern Ocean, forming a link between primary production and large predators. Krill produce large, faecal pellets (FP) which can form a large component of mesopelagic particulate organic carbon (POC) fluxes. However, the patchy distribution of krill swarms, highly variable pellet composition, and variable sinking and attenuation rates means that these episodic, but potentially large, carbon fluxes are difficult to sample or model. We measured particle flux and type using Marine Snow Catchers (MSC) in the marginal ice zone near the South Orkneys, Antarctica. Krill FP were the dominant component of the POC flux in the upper 200 m (typically 60-85%). FP sinking velocities measured onboard were highly variable (15-507 m d) but overall high, with mean equivalent velocities of 172, 267, and 161 m d at our three stations. The high numbers of krill FP sinking through the mesopelagic suggest that krill FP can be transferred efficiently and/or that rates of krill FP production are high. We compared our direct MSC-derived estimates of krill FP POC flux (33-154 mg C m d) and attenuation to estimates of krill FP production based on previous measurements of krill density and literature FP egestion rates, and estimated net krill FP attenuation rates in the upper mesopelagic. Calculated attenuation rates are sensitive to krill densities in the overlying water column but suggest that krill FP could be transferred efficiently through the upper mesopelagic, and, in agreement with our MSC attenuation estimates, could make large contributions to bathypelagic POC fluxes. Our study contrasts with some others which suggest rapid FP attenuation, highlighting the need for further work to constrain attenuation rates and assess how important the contribution of Antarctic krill FP could be to the Southern Ocean biological carbon pump. [ABSTRACT FROM AUTHOR]

In water-lubricated pipeline transportation of heavy oil and bitumen, a thin oil film typically coats the pipe wall. A detailed study of the hydrodynamic effects of this fouling layer is critical to the design and operation of oil-water pipelines, as it can increase the pipeline pressure loss (and pumping power requirements) by 15 times or more. In this study, a parametric investigation of the hydrodynamic effects caused by the wall coating of viscous oil was conducted. A custom-built rectangular flow cell was used. A validated CFD-based procedure was used to determine the hydrodynamic roughness from the measured pressure losses. A similar procedure was followed for a set of pipe loop tests. The effects of the thickness of the oil coating layer, the oil viscosity, and water flow rate on the hydrodynamic roughness were evaluated. Oil viscosities from 3 to 21300 Pa s were tested. The results show that the equivalent hydrodynamic roughness produced by a wall coating layer of viscous oil is dependent on the coating thickness but essentially independent of oil viscosity. A new correlation was developed using these data to predict the hydrodynamic roughness for flow conditions in which a viscous oil coating is produced on the pipe wall. [ABSTRACT FROM AUTHOR]

PurposeDemands on publicly funded ophthalmic services worldwide continue to increase with new treatments, waiting time targets, working time limits, and restricted budgets. These highlight the necessity to develop innovative ways of utilising existing capacity more effectively.MethodA new regional, fully electronic ophthalmic-referral service with digital imaging was trialled using existing information-technology (IT) infrastructure. Following successful pilot study, the service was rolled out regionally. Service delivery data was prospectively collated for all the attendances in the year prior to (2006) and the year following (2008) introduction.ResultsComparing 2006 against 2008, median waiting times reduced (14 vs 4 weeks), and fewer new patients were observed (8714 vs 7462 P<0.0001), with 1359 referrals receiving electronic diagnosis (e-diagnosis). New patient did not arrive (635 vs 503 P<0.0001) and emergencies also reduced (2671 v 1984 P<0.0001).DiscussionNovel use of existing IT infrastructure improves communication between primary and secondary care. This promotes more effective use of limited outpatient capacity by retaining patients with non-progressive, asymptomatic pathology in the community, whilst fast-tracking patients with sight-threatening disease. Resultant significant, sustained improvements in regional service delivery point to a simple model that could easily be adopted by other providers of universal healthcare globally. [ABSTRACT FROM AUTHOR]

PurposeTo determine current knowledge and opinion on revalidation, and methods of cataract surgery audit in Scotland and to outline the current and future possibilities for electronic cataract surgery audit.MethodsIn 2010 we conducted a prospective, cross-sectional, Scottish-wide survey on revalidation knowledge and opinion, and cataract audit practice among all senior NHS ophthalmologists. Results were anonymised and recorded manually for analysis.ResultsIn all, 61% of the ophthalmologists surveyed took part. Only 33% felt ready to take part in revalidation, whereas 76% felt they did not have adequate information about the process. Also, 71% did not feel revalidation would improve patient care, but 85% agreed that cataract surgery audit is essential for ophthalmic practice. In addition, 91% audit their cataract outcomes; 52% do so continuously. Further, 63% audit their subspecialist surgical results. Only 25% audit their cataract surgery practice electronically, and only 12% collect clinical data using a hospital PAS system. Funding and system incompatibility were the main reasons cited for the lack of electronic audit setup. Currently, eight separate hospital IT patient administration systems are used across 14 health boards in Scotland.ConclusionRevalidation is set to commence in 2012. The Royal College of Ophthalmologists will use cataract outcome audit as a tool to ensure surgical competency for the process. Retrospective manual auditing of cataract outcome is time consuming, and can be avoided with an electronic system. Scottish ophthalmologists view revalidation with scepticism and appear to have inadequate knowledge of the process. However, they strongly agree with the concept of cataract surgery audit. The existing and future electronic applications that may support surgical audit are commercial electronic records, web-based applications, centrally funded software applications, and robust NHS connections between community and hospital. [ABSTRACT FROM AUTHOR]

AimPostoperative outcome of trainee glaucoma surgery compared with glaucoma specialist consultant surgery. Survey of Scottish consultant ophthalmologists' views on trainee surgery.MethodRetrospective analysis of 128 trainee and 176 consultant trabeculectomies, with minimum postoperative follow-up of 2 years. Prospective postal survey of 80 Scottish consultant ophthalmologists.ResultsTrainees operated mainly on cases of chronic open angle glaucoma, while consultants operated on significantly more complicated glaucomas (P=0.0004). Trainee cases had more bleb leaks (P=0.01), hypotony (P=0.05), early (P=0.01) and late (P=0.03) return to theatre, and bleb interventions (P=0.01). Trainee mitomycin trabeculectomies were associated with higher rates of return to theatre (P=0.002), and cataract extraction within the first postoperative year (P=0.002). Trainee cases of pseudoexfoliation had more early complications (P=0.024), and trainee cases of low tension required more bleb interventions (P=0.05). There was no significant difference (P>0.05) between average intra-ocular pressure control (IOP) at postoperative visit year 1 between consultant (14.3 mm Hg) and trainee (13.9 mm Hg) cases. More than 50% of the 80 Scottish ophthalmology consultants surveyed, indicated that glaucoma surgery training requirements should be retained.ConclusionsTrainee trabeculectomy cases showed significantly higher rates of early complications, return to theatres, and bleb interventions compared with consultant cases. Satisfactory IOP control was achieved in both groups at postoperative year 1. Trainee cases require careful preoperative selection, avoiding complicated glaucomas including pseudoexfoliation and low tension, and those that require mitomycin. The majority of Scottish consultants wish to retain glaucoma surgery within the remit of generic training. [ABSTRACT FROM AUTHOR]

AimsA study to assess the feasibility, safety, and clinical effectiveness of electronic referral—with and without images—of patients directly from optometrists in primary care to the hospital eye service (HES) in contrast to the traditional paper-based referral, through the general practitioner (GP).MethodsThree optometry practices sent consecutive referrals with images through the NHS Net to the HES. The standard General Ophthalmic Service form was electronically redesigned with additional information on patient choice for advice, appointment, or surgery. All paper referrals to the HES from the same three optometry practices before the study period were analysed (control group A) as were all paper referrals from the remaining optometrists in Fife (control group B).ResultsA total of 346 electronic referrals were received over 18 months. 218 (63%) were classified as requiring and 128 (37%) as not requiring a HES appointment. The latter were subsequently examined with unexpected pathology found in three cases (glaucoma, macular pigment epithelial detachment, and possible peripheral retinal tear). In both groups, the major pathologies reported were macular degeneration, cataract, glaucoma, diabetic retinopathy, and abnormal retinal appearances. A total of 17 (15%) patients in group A and 26 (8.4%) patients in group B were classified as not requiring HES appointment. These control groups indicate that approximately 10–15% of paper referrals are not seen in the HES. To summarise, therefore, 63% of people referred by the optometrist directly using electronic referral (with or without images) were given a HES appointment compared to 85% of people referred through the traditional paper method (without images) through their GP.ConclusionElectronic referral with images to the HES is safe, speedy, efficient, and clinically accurate given some limitations and avoids unnecessary consultation in 37% of referrals.Eye (2009) 23, 1134–1140; doi:10.1038/eye.2008.196; published online 4 July 2008 [ABSTRACT FROM AUTHOR]

AimThe management of patients on antiplatelet and anticoagulation therapy (APACT) in glaucoma surgery currently has no specific recommendations. We aimed to establish the risk of haemorrhagic complications and surgical outcome in patients on APACT in glaucoma surgery.MethodsWe retrospectively examined 367 consecutive trabeculectomies performed between 1994 and 1998. Preoperatively 60 (16.4%) patients were on APACT (55 on aspirin and five on warfarin). The incidence of hyphaema and haemorrhagic complications between patients with and without APACT was documented. Surgical success was defined in two categories as an intraocular pressure (IOP) <21 mmHg and an IOP <16 mmHg 2 years following trabeculectomy with and without antiglaucoma medication.ResultsNone of the patients on aspirin suffered significant intra or postoperative haemorrhage. Aspirin was associated with a significantly higher risk of hyphaema (P=0.0015) but this was not found to significantly affect IOP control at 2 years. Patients on warfarin suffered haemorrhagic complications and trabeculectomy failure.ConclusionsAspirin appears to be safe to continue with during trabeculectomy. Patients on aspirin have an increased risk of hyphaema following trabeculectomy. This however does not appear to affect surgical outcome. Warfarinised patients are at risk of serious bleeding complications. They require careful monitoring pre- and postoperatively and are at risk of trabeculectomy failure.Eye (2007) 21, 598–603. doi:10.1038/sj.eye.6702277; published online 3 March 2006 [ABSTRACT FROM AUTHOR]

Domestic chickens (Gallus gallus) are an excellent model in which to evaluate developmental toxicity and oxidative stress because of their high sensitivity to 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD). The goal of this study was to measure the effects of environmentally relevant doses of TCDD on endogenous hepatic antioxidant enzyme activity in hatchling chickens. The vehicle (sunflower oil) or 2, 20, or 200 pg/g TCDD was injected into chicken eggs before incubation. On hatching, livers were harvested and quickly frozen. The changes in activity of antioxidant enzymes, including glutathione peroxidase (GPx), glutathione reductase (GRx), copper zinc superoxide dismutase (SOD), and catalase (CAT) were determined as indicators of oxidative stress. TCDD exposure was associated with a significant suppression of the activities of the protective endogenous enzymes GPx, GRx, and SOD in the liver, even at the lowest dose. CAT activity was also suppressed, but not significantly. The measured decreases were 37% to 63% for GPx, 50% to 58% for GRx, 30% to 40% for SOD, and 16% to 24% for CAT. Noncomplex dose–response relationships were evident in GPx and GRx, whereas SOD and CAT curves were U-shaped. These results demonstrate that a decreased ability to scavenge reactive oxygen species may result from developmental TCDD exposure at very low doses, contributing to oxidative stress and thus to the embryotoxicity of TCDD. [ABSTRACT FROM AUTHOR]

AimAssessment of trabeculectomy in South-East Scotland (SESTS) with comparison to National Survey of Trabeculectomy (NST) and outcomes of consultant and trainee surgery.MethodA retrospective study of 304 consecutive, primary trabeculectomies, in two Scottish centres (Edinburgh and Dunfermline) with two glaucoma specialists and higher surgical trainees, was performed. The study group had primary open angle glaucoma (65.5%), pseudoexfoliation (6.9%), normal tension glaucoma (7.6%), pigment dispersion syndrome (1.6%), and other complicated glaucoma (18.4%). All patients underwent trabeculectomy by the glaucoma specialist (57.6%) and higher surgical trainee (42.4%) with close scrubbed supervision.ResultsCompared to the NST, the waiting time for surgery (<3 months) was significantly less in the SESTS (P<0.001). There was also significantly more use of intraoperative antimetabolites (P<0.01), bleb intervention (P<0.001), and a higher rate of early complications (P<0.025). There was no significant difference in outcome at intraocular pressure (IOP)<2/3 listing IOP (qualified and unqualified) between the SESTS and the NST. Significantly, more patients achieved an unqualified success of IOP<21 mmHg (P<0.01) and an unqualified success of IOP<16 mmHg in the SESTS than the NST (P<0.05). At 1 year post surgery, visual loss of greater than one Snellen line was more common in the NST (P<0.01) as was the use of anti-glaucoma medication (P<0.001). Trainee cases returned to theatre more frequently (P<0.025) and merited more bleb intervention (P<0.01) than consultant cases, but the long-term outcome was similar.ConclusionOur study highlights significant changes in the practice and outcome of trabeculectomy compared to the national survey conducted a decade ago.Eye (2007) 21, 46–51. doi:10.1038/sj.eye.6702118; published online 7 October 2005 [ABSTRACT FROM AUTHOR]

AimTo set-up a glaucoma electronic patient record (GEPR) and study referral details to a new glaucoma service, concentrating on high-risk patients.MethodA GEPR was designed using the pre-existing hospital information technology (IT) infrastructure. Referral details of all new patients to the glaucoma service were completely electronically entered and analysed.ResultsA GEPR was successfully established. A total of 402 referrals were studied. In all, 43% (40) of high-risk clinic patients (IOP>29 mmHg, or C/D ratio >0.8 or moderate to advanced visual field defects) had to wait longer than 8 weeks from GP referral to be seen at the glaucoma service. Of these, nine patients lost more than one line of Snellen's visual acuity attributable to glaucoma. The optometrist failed to document IOP in 17%, fundoscopy in 30%, and visual fields in 45% of all referrals.ConclusionsA GEPR can be introduced in an NHS setting without disruption of clinical care and ophthalmic training, and facilitates detailed, accurate and rapid audit. Study of high-risk glaucoma referrals showed inadequate optometric referral details and poor prioritisation of urgent cases. This information is being utilised with the cooperation of local optometrists to refine the pattern of glaucoma referrals.Eye (2005) 19, 956–962. doi:10.1038/sj.eye.6702008; published online 29 July 2005 [ABSTRACT FROM AUTHOR]

AIMS: To evaluate the current visual status and ophthalmic history of a sample of elderly patients with fractured neck of femur and to study the relationship between visual status and demographic factors. METHODS: A four-centre study of all patients admitted to hospital with fractured neck of femur. The setting was two district (Ayr, Dunfermline) and two teaching (Glasgow, Dundee) hospitals in Scotland. The study examined 537 patients aged 65 years and over admitted with acute fractured neck of femur to hospital. RESULTS: Bilateral visual impairment (binocular visual acuity worse than 6/12) was found in 239 of 518 patients (46%). Of this group, the principal causes for visual deficit were untreated cataract (49%), macular degeneration (21%), uncorrected refractive error (17%), and glaucoma (3%).The visually impaired group were more likely to have symptomatic visual complaints (58 vs 26%), however, were less likely to be under optometric care (71 vs 85%). A higher proportion of the group with visual impairment lived in areas of social deprivation (40 vs 26%). CONCLUSIONS: Patients with fractured neck of femur represent a frail elderly group that have poorer vision than that documented in any other elderly population. The visual defect was potentially remediable in the majority of cases but this group of individuals are not generally in touch with the ophthalmic services. Social deprivation appears to be associated with this groups' inability to access ophthalmic care.Eye (2005) 19, 652–656. doi:10.1038/sj.eye.6701610 Published online 27 August 2004 [ABSTRACT FROM AUTHOR]

Axenic growth of a mixotrophic alga, Ochromonas sp., was compared in several inorganic and organic media, and in the presence of live bacteria under nutrient-replete and low-nutrient conditions. Axenic growth in the light was negligible in inorganic media with or without the addition of glucose. Addition of vitamins increased growth rate, but average cell size declined, resulting in no net increase in biomass. Supplementing axenic cultures with a more complex organic substrate resulted in moderate growth and higher maximal abundance (and biomass) than in the inorganic media with added vitamins. The absence of light did not greatly affect population growth rate in the presence of complex dissolved organic compounds, although cell size was significantly greater in the light than in the dark. The highest growth rates for the alga (up to 2.6 d?1) were measured in treatments containing live bacteria. Increases in cell number of Ochromonas sp. in the presence of bacterial prey were similar in the light and dark, although chloroplast and cell sizes differed. Bacterial abundance was reduced and dissolved phosphorus and ammonia were rapidly released in bacterized cultures in the light and dark, indicating high rates of bacterial ingestion and suggesting an inability of the alga to store or utilize N and P in excess of the quantities required for heterotrophic growth. Low-nutrient conditions in the presence of bacteria were promoted by adding glucose to stimulate bacterial growth and the uptake of N and P released by algal phagotrophy. Subsequent decreases in dissolved N and P following the addition of glucose corresponded to a second period of rapid growth of the alga in both light and dark. This result, combined with evidence for slow axenic growth of this strain, indicated that nutrient acquisition for this species in the presence of bacteria was accomplished primarily via ingestion of bacteria. [ABSTRACT FROM AUTHOR]

Studies reported to date have shown a good depilatory response from patients treated with the normal mode ruby laser (NMRL) over 12 weeks, but a low response over a time period greater than this. Previous publications have suggested that this could be accounted for by the apparently poor skin penetration of laser light and so this study attempted to assess whether this was indeed the case. Skin samples of varying thicknesses were taken from six Caucasian patients and their depths measured. Each was laid individually on an energy meter before having pulses from an NMRL compatible with clinical doses (4.75 J/cm2, 9.24 J/cm2 and 13.41 J/cm2) fired on the epidermis. Several samples had the laser fired repetitively on the surface to assess whether this caused any change in laser/skin fluence depth profiles. Repetitive firing of the NMRL on the epidermis of skin samples did not alter the energy recorded by the meter beneath. The fluence/depth profiles were constructed showing the majority of energy was lost within the first 1 mm of the skin surface (50%) which then further reduced over distance but at a much slower rate. The maximum depth of penetration was 14.8 mm (SD +/- 0.478) which appeared to be a function of wavelength and not fluence. The results suggest that laser penetration of skin should be adequate for generating enough heat at the hair bulge and bulb, potentially causing permanent damage. The implications of this study are that it is probably the presence of the correct chromophore in large enough amounts which is required for successful permanent depilation to occur. [ABSTRACT FROM AUTHOR]

Aromatic L-amino acid decarboxylase (AADC) is a relatively non specific enzyme involved in the biosynthesis of several classical neurotransmitters including dopamine and 5-hydroxytryptamine (5HT; serotonin). AADC does not catalyse the rate limiting step in either pathway, but is rate limiting in the synthesis of 2-phenylethylamine (2PE) which is a positive modulator of dopaminergic transmission and a candidate natural psychotogenic compound. We and others have proposed that polymorphism in AADC resulting in altered 2PE activity might contribute to the pathogenesis of psychosis. In order to test this hypothesis, we have used denaturing high performance liquid chromatography (DHPLC) to screen 3943 bases of the AADC gene and its promoter regions for variants that might affect protein structure or expression in 15 unrelated people with schizophrenia, and 15 unrelated people with bipolar disorder. Three polymorphisms were identified by DHPLC: a insertion/deletion polymorphism in the 5′ UTR of the neuronal specific mRNA (g.-33-30delAGAG, bases 586-589 of GenBank M77828), a T>A variant in the non-neuronal exon 1 (g.-67T>A, GenBank M88070), and a G>A polymorphism within intron 8 (g.IVS8 +75G>A, GenBank M84598). Case-control analysis did not suggest that genetic polymorphism in the AADC gene is associated with liability for developing schizophrenia or bipolar disorder. [ABSTRACT FROM AUTHOR]

Neurotensin (NT) is an endogenous tridecapetide cleaved from a precursor proneurotensin/proneuromedin protein. NT Iocalises within dopaminergic neurones in the mesocortical, mesolimbic and nigrostriatal systems and it is now clear that NT can selectively modulate dopaminergic neurotransmission. These anatomical and functional connections have led to the hypothesis that NT dysfunction might contribute to the pathogenesis of neuropsychiatric disorders in which disordered dopaminergic neurotransmission is suspected, particularly schizophrenia. The latter hypothesis has been supported circumstantially by the observation that central administration of NT produces effects similar to those produced by the peripheral administration of atypical antipsychotics, and more directly by studies showing levels of NT in cerebral spinal fluid (CSF) is lower in schizophrenics than in controls. To allow such hypotheses to be tested, we used denaturing high performance liquid chromatography (DHPLC) to identify three sequence variants in the neurotensin gene (NTS) that might alter NT structure or expression. However, using a case-control study design and a novel genotyping system based upon a primer extension protocol and HPLC detection, we found no evidence to support the hypothesis that variation in the proneurotensin gene contributes to susceptibility to schizophrenia. [ABSTRACT FROM AUTHOR]

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The relative importance of autotrophic flagellates, desmids, cyanobacteria, and ciliates as food for Daphnia magna was examined using cohort life tables. Each cohort was fed a single food type at a given concentration, and comparisons among each type were made. Algal feeding treatments included three levels of young (7 to 14 days old) Chlamydomonas reinhardi (Chlorophyta, Chlamydomonadacae), two levels of senescent (> 14 days old) C. reinhardi, two levels of Cryptomonas sp. (Chlorophyta, Cryptomonadacae), two levels of Staurastrum sp. (Chlorophyta, Desmidacae), four levels of young (7 to 15 days old) or senescent (> 15 days old) Microcystis aeruginosa (Cyanophyta, Chlorococcacae), and a no-food treatment. The ciliates Cyclidium sp. and Paramecium caudatum were also presented at concentrations of 1 or 10 cells/ml, as well as mixtures of C. reinhardi (10/ml) and Cyclidium (1/ml) or P. caudatum (1/ml). Daphnia growth, reproduction, and survivorship were highest when C. reinhardi or Cryptomonas were the food source, while those starved or fed M. aeruginosa had shorter survivorship and lower growth and reproduction. Daphnia grew and had high survivorship when fed P. caudatum, but even though eggs were produced, most were aborted after 2 or 3 days. Staurastrum and Cyclidium produced intermediate growth and survivorship, but reproduction was seen only in the 10 Staurastrum/ml treatment. Carbon and nitrogen content were general indicators of nutritional value. However, growth, reproduction, and survivorship were higher in some cohorts fed treatments containing relatively low levels of carbon and nitrogen. Other cohorts were short-lived and did not reproduce, despite being fed much higher levels of carbon and nitrogen. The results also suggest that green algae are nutritionally valuable for Daphnia, whereas cyanobacteria are not. As measured by life-table parameters, the nutritional value of ciliates was variable, with some being poor food sources. Thus, the potential of ciliates as a trophic link between microbial production and higher trophic levels may vary with the ciliate community structure. Our results suggest that ciliates alone were insufficient as a food source to support Daphnia population growth. [ABSTRACT FROM AUTHOR]

Coatings of CeO2 derived from inorganic sol-gel dispersions were applied to type 304 bright annealed stainless steel (British Standard 1449 type 304S31) coupons and subjected to heat treatments at 450 and 550 °C. The coatings, 0.5 μm thick, were transparent, adherent, and stable. The aqueous corrosion properties of the coated coupons in 1 molar NaCl were then studied by potentiodynamic polarization measurements and electrochemical impedance spectroscopy. The derived corrosion parameters were then compared with similarly heat-treated, uncoated 304SS coupons. The results indicate that the application of a CeO2 coating, heat treated at 550 °C, improves the corrosion rate as compared to an uncoated heat-treated coupon. The polarization curve for the 450 °C heat-treated, coated coupon showed passive behavior compared to transpassive for the uncoated specimen. The impedance spectrum data for the uncoated, as-received coupon could be modeled using a resistor in series with a parallel capacitor resistor combination “Randles” equivalent circuit. A coated coupon, heat treated at 550 °C, could be modeled using a more complex equivalent circuit involving a constant phase element, due to the CeO2 coating. Modeling of the impedance characteristics for the oxidized coupons required the addition of a second series element consisting of a parallel resistor capacitor combination to give a Chi square statistic fit of X2 < 5 X 10-4. [ABSTRACT FROM AUTHOR]

A study was undertaken to determine the effect of microstructures produced by different ingot processing techniques on the fatigue properties of a 7050 aluminum alloy. The different microstructures investigated were produced by hot-rolling to simulate commercial processing (CP) methods or intermediate thermomechanical treatments (ITMT). Characterization of the microstructures revealed that the CP 7050 material was partially recrystallized (<50 pct) due to the use of hot-rolling as the final deformation step. The ITMT materials were examined in the as-recrystallized (AR) condition or in AR + hot rolled condition (AR + HR). Results of the investigation showed that total fatigue life, both low and high cycle, were not greatly affected by the grain structures of the experimental materials. However, metallographic studies indicated that crack initiation is probably more difficult in the fine-grained AR material. The results of fatigue crack growth tests showed that higher crack growth rates observed at low Δ K values for ITMT {dy7050} were most likely due to the detrimental effects of undissolved AlCuMg particles. These particles, which also contribute to low fracture toughness and higher crack growth rates at high Δ K levels, are formed during a furnace-cooling step in the ITMT processing schedule. [ABSTRACT FROM AUTHOR]

The addition of 0.18 at. Pct Mg to a 2XXX (Al-2.6 at. Pct Cu) aluminum alloy was found to increase strength in all types of commercially important tempers. The effect of the Mg addition was maximum in artificially aged materials which were cold worked prior to aging. However, in naturally aged materials, the benefit to strength from the addition of Mg decreased with cold work. Transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) were used to explain the improved properties based on the microstructure. Mechanisms by which the Mg addition alters the microstructure and improves the yield strength are proposed. [ABSTRACT FROM AUTHOR]

The usefulness of the fluorescent probe ruthenium tris(2,2′-dipyridyl) dichloride hydrate (RTDP) for the quantitative imaging of oxygen in single cells was investigated utilizing fluorescence lifetime imaging. The results indicate that the fluorescence behavior of RTDP in the presence of oxygen can be described by the Stem-Volmer equation. This shows that fluorescence quenching by oxygen is a dynamic quenching process. In addition, it was demonstrated that the fluorescence lifetime of RTDP is insensitive to pH, ion concentration, and cellular contents. This implies that a simple calibration procedure in buffers can be used to quantify oxygen concentrations within cells. First fluorescence imaging experiments on J774 macrophages show a nonuniform fluorescence intensity and a uniform fluorescence lifetime image. This indicates that the RTDP is heterogeneously partitioned throughout the cells, while the oxygen concentration is constant. [ABSTRACT FROM AUTHOR]

The development of laser Doppler flowmetry (LDF) has provided a real-time, reliable method for monitoring capillary perfusion in multiple tissues. LDF has potential for the experimental and clinical assessment of bone blood flow. To compare the accuracy and ease of use of two commercially available laser Doppler flowmeters with different mechanisms for processing the Doppler-shifted component of light, estimates of bone blood flow were obtained in a sheep model using the two systems, and the values derived then compared with estimates of bone blood flow also obtained in a sheep using the technique of injection of labeled microspheres. The single-channel laser Doppler flowmeter, the LD 5000, processes the reference and Doppler-shifted beams on the surface of a single photodetector using optical heterodyning for measurement. The dual-channel flowmeter, the Periflux 2, uses two optical fibers to transmit reference and Doppler-shifted light to two separate photodetectors. The differential amplification and detection system improves the signal-to-noise ratio. Measurement of both metaphyseal (cancellous) and diaphyseal (cortical) blood flow using both LDF systems was compared with values obtained with an injection of 85Sr-labeled microspheres in three sheep. The LDF measurements were repeated after occlusion of the left femoral artery, and a 46Sc microsphere injection was performed prior to animal sacrifice. Two of the animals developed vasomotor instability, resulting in poor correlation between the measurements obtained with the Periflux 2, which is motion sensitive, and the values obtained with the microsphere method. High correlation was apparent in two of the three animals for the LD 5000 and the microsphere values.(ABSTRACT TRUNCATED AT 250 WORDS) [ABSTRACT FROM AUTHOR]

The acute phase response to chemically-induced organ damage involves inflammation and the production of leukotrienes. The liver ordinarily takes up, metabolizes and excretes into bile cysteinyl leukotrienes, but the effect of hepatic injury on these processes is unknown. The hepatic uptake and biliary excretion of LTC was studied in male Sprague-Dawley rats after exposure to either streptozotocin (45 mg/kg iv 30 days before experimentation), estradiol-17 β-valerate (1mg/kg sc once a week for 3 weeks) or lipopolysaccharide/ d-galactosamine (33 μg/kg ip; 300 mg/kg ip at 6 h and 3 h, respectively, before experimentation). Acute liver injury is produced by these treatment paradigms. Glucose concentrations and activities of several marker enzymes in plasma were measured to demonstrate hepatic injury. Biliary excretion ofH-LTC was similar to normal control rats in the three types of acute liver injury. Bile flow rates afterH-LTC injection were reduced in lipopolysaccharide-pretreated rats and increased in estradiol-treated animals. Total biliary excretion of leukotrienes was not altered in any disease group. Thus, these models of acute hepatic injury do not appear to influence the hepatobiliary clearance of leukotrienes. [ABSTRACT FROM AUTHOR]

Isolation and partial sequencing of human T-lymphotropic virus type I (HTLV-I) variants from inhabitants of Papua New Guinea (PNG) and the Solomon Islands has confirmed the existence of virus infection in Melanesian populations. To determine the geographical distribution of seropositivity to HTLV-I in PNG we have tested 2907 serum and plasma samples collected between 1972 to 1991 from 16 different population groups. Samples were screened using a particle agglutination assay and confirmed by p21e-enhanced Western immunoblot (WB). From a total of 94 screen positive samples run on WB, 56 (60%) were confirmed positive (positive for both env and gag products) and 38 (40%) were WB-indeterminate ( gag products only). The prevalence of WB-confirmed antibodies to HTLV-I in lowland and island populations ranged from 0 to 5.4%. There were no confirmed antibody positives in the highland populations surveyed. Geographically isolated populations living on the fringes of the highlands ranged in seropositivity from 0.2 to 5.8%. Two of the subjects surveyed gave WB antibody patterns characteristic of HTLV-II rather than HTLV-I infection. [ABSTRACT FROM AUTHOR]

Serum samples collected in 1984 during a malariometric survey of two villages in the East Sepik Province of Papua New Guinea were tested for antibodies to HTLV-I. None of the villagers showed any symptoms suggestive of retrovirus infection. Eighteen of the 186 (9.5%) sera tested at that time were found to be positive. Blood samples were subsequently obtained from fifteen of the eighteen positives and subjected to analysis by enzyme-linked immunosorbent assay (ELISA), radioimmuno assay (RIA), radioimmunoprecipitation assay (RIPA), and Western blot (WB). Fourteen of the fifteen gave a positive ELISA response, but none were unequivocally positive by p 24 RIA. All sera tested were reactive to gag antigens by WB, but gave 'indeterminate' results currently accepted criteria. Notably absent from the WB profiles of all of the study subjects was an antibody response to HTLV-I envelope protein gp 46. It is possible that these antibody responses are directed against a variant of HTLV-I or to a novel retrovirus which possesses core antigens similar to those of HTLV-I but has different envelope antigens. Until a virus is isolated, or the viral genome is identified in infected lymphocytes, the possibility remains that the response may be due to factors unrelated to retrovirus infection. [ABSTRACT FROM AUTHOR]

Congenital anomalies of the genitourinary system represent the commonest fetal anomaly. The sonographic findings in hydronephrosis, multicystic kidney (dysplastic kidney) polycystic kidney, and renal agenesis are reviewed. [ABSTRACT FROM AUTHOR]

Ultrasound is of value in the investigation and management of infertility in males and females. Monitoring of follicle growth and follicle aspiration is well accepted and commonly used. Defects of ovulation such as polycystic ovary disease or luteinized unruptured follicle syndrome may be recognized. Problems related to the union of the sperm and ova may also be seen. Obstructing lesions such as endometriosis and fibroids may be investigated by ultrasound. In males the principle use of ultrasound lies in the examination of the seminal vesicles, vas deferens, and ejaculatory ducts to see whether they are intact and unobstructed. Defective sperm motility may be due to varicoceles which are easily detected by the use of ultrasound. [ABSTRACT FROM AUTHOR]

Although there is good evidence that carcinomas of the prostate are usually seen as echopenic masses within the external zone of the prostate, it is unclear how often an echopenic mass has an origin other than carcinoma of the prostate. Technical problems at the periphery of the gland not uncommonly create echopenic areas on an artifactual basis. Whether ultrasound will prove to be a satisfactory screening method for the detection of carcinoma of the prostate is yet to be decided. Prospective studies are in progress, but it has not yet been established whether prostate screening is a worthwhile procedure. The best possible equipment is required to detect these subtle lesions; cheap equipment will probably not give adequate results. [ABSTRACT FROM AUTHOR]

Measurements of physical properties of the intact human skin are described. An analysis of the measurements yields parameters that characterize elastic, visco-elastic and plastic properties. Between 6 and 61 years the elastic component of the extensibility of the skin under torsional conditions increases with age. The visco-elastic and plastic components are constant up to an age of fourty; at higher ages they show a small tendency to increase. Moduli of elasticity of the intact human skin derived from the torsion measurements yield values between about 2×10 N/m and 10 N/m, the highest values corresponding to the youngest age. From these values the moduli of elasticity of the elastic fibres in the living skin are estimated between about 2×10 N/m and 10 N/m. [ABSTRACT FROM AUTHOR]

Duodenal ulcer as a disease is a composite of interrelated physiologic, biochemical and psychic disturbances. The efforts of the surgeon to relieve the symptoms by antral gastric resections and/or vagotomy have been successful except for a small percentage of patients. The recent reports of finding of certain endocrine tumors associated with the refractive ulcer patient marks another major advance in the understanding of the ulcer problem. [ABSTRACT FROM AUTHOR]

Thirty-three patients with fractures of the thoracolumbar spine were treated by fusion and Harrington instrumentation after early reduction and stabilisation by postural reduction or halo-bifemoral traction. The rod-long-fuse-short technique was used. Postoperatively, all patients were mobilised with an external support. The mean follow-up was 6 years (range 1-13 years). Twenty-eight patients were pain-free, three patients needed sporadic pain medication. One patient was not working due to pain in his leg. One patient had constant pain. Twenty-three patients returned to work. The mean kyphosis increased from 8 degrees postoperatively to 13 degrees at follow-up. [ABSTRACT FROM AUTHOR]

The kinematics of inertial particles suspended in the near-wall region of Newtonian and non-Newtonian turbulent channel flows was experimentally investigated. The non-Newtonian fluid was a homogeneous solution of 90 part per million of a polyacrylamide polymer in water with 66% drag reduction. All the experiments were performed at the same volumetric flow rate with Reynolds number of 34,300 based on bulk velocity, channel height, and the kinematic viscosity of water. The inertial particles were 250-μm glass beads with St of 35 (in water) at a volumetric concentration of 0.05%. A time-resolved two-dimensional particle tracking velocimetry was used to record particle images at acquisition frequency of 17.6 kHz and detect trajectory of flow tracers and the glass beads. The recorded data were processed using a two-dimensional particle tracking algorithm to obtain the Lagrangian kinematics of the beads. The comparison between laden flows of water and polymer solution showed reduction of number density of the beads and their momentum in the vicinity of the wall in the polymeric flow. The polymer solution remarkably reduced the wall-normal and shear Reynolds stresses of the beads, but had a negligible effect on their streamwise Reynolds stress. The wall-normal fluctuation of the beads reduced in the polymeric flow and their trajectories became parallel with the channel wall. Results also showed that the ejection and sweep motions were not the major mechanism for wall-normal distribution of the beads in the polymeric flow. Outcomes suggest that drag-reducing polymer solutions have the potential of reducing erosive wear in particle-laden pipelines. [ABSTRACT FROM AUTHOR]

Two patients with sleeve fractures of the patella and tibial tuberosity respectively are described. Our two cases demonstrate that the diagnosis can be difficult; patella alta and ossification in the patellar tendon are complications of conservative treatment. Early diagnosis and operative reduction and fixation are mandatory. [ABSTRACT FROM AUTHOR]

Biological oceanic processes, principally the surface production, sinking and interior remineralization of organic particles, keep atmospheric CO2 lower than if the ocean was abiotic. The remineralization length scale (RLS, the vertical distance over which organic particle flux declines by 63%, affected by particle respiration, fragmentation and sinking rates) controls the size of this effect and is anomalously high in oxygen minimum zones (OMZ). Here we show in the Eastern Tropical North Pacific OMZ 70% of POC remineralization is due to microbial respiration, indicating that the high RLS is the result of lower particle fragmentation by zooplankton, likely due to the almost complete absence of zooplankton particle interactions in OMZ waters. Hence, the sensitivity of zooplankton to ocean oxygen concentrations can have direct implications for atmospheric carbon sequestration. Future expansion of OMZs is likely to increase biological ocean carbon storage and act as a negative feedback on climate change. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article on the medical outcome of trabeculectomies performed by trainee and consultants by R. Troutbeck and colleagues.

For several years NO2 and OClO, two species important to understanding ozone destruction in the Antarctic stratosphere, have been measured at Arrival Heights, Antarctica by two groups: New Zealand's National Institute of Water and Atmospheric Research (NIWA) and the NOAA Aeronomy Laboratory in Boulder, Colorado. Using data independently collected by these two groups during the Austral spring of 1996, it is shown that the two data sets are in extremely close agreement. Besides offering validation of the instrumentation and analysis techniques of both groups, this result provides confidence in the more complete history of these species gained by combining the two data sets. [ABSTRACT FROM AUTHOR]