Lower Ouse Research Articles

Protective factors against preterm infants to develop significant patent ductus arteriosus

Identifying preterm infants with a higher likelihood of spontaneous patent ductus arteriosus (PDA) closure would be desirable. This study aimed to examine daily PDA status during the first week of life for very low birthweight (VLBW, <1500g) preterm infants and to develop a scoring system to predict spontaneous PDA closure. We enrolled VLBW infants admitted between January 2016 and January 2017 and performed daily echocardiographic screening for PDA existence. Oxygen index (OI, mean airway pressure×fraction of inspired oxygen/partial pressure of arterial oxygen) was applied to represent the respiratory condition. A total of 215 VLBW infants were enrolled, and the accumulative incidence of spontaneous PDA closure by age 1 week was 80%, 70%, and 34% for infants born of gestational age (GA) ≥30, 28-29, and ≤27 weeks, respectively. Of these 215 infants, 184 infants entered the second phase to establish the scoring system. Infants with spontaneous PDA closure were more mature (GA 29.2±2.3 vs. 26.9±2.3 weeks, p<0.001), had lower OI (2.8±2.2 vs. 5.6±5.3, p<0.001) and were less likely to need endotracheal intubation (23% vs. 68%, p<0.001). Using the receiver operating characteristics curve, OI <2.5 was determined favoring higher PDA closure incidence. The score was calculated based on the odds ratio generated in multiple regression: 4, 3 and 1 points for GA ≥30, 28-29 and≤27 weeks, 2 and 1 points for OI <2.5 and≥2.5, and 3 and 1 points for without and with endotracheal intubation. Using score ≥6 to predict PDA closure, the sensitivity and specificity were 0.77 and 0.72. A score made up of GA, OI and need for intubation was proposed to predict spontaneous PDA closure by age 1 week, which could be helpful to clinicians in the management of PDA in preterm infants.

A Multiscale Evaluation of the Coupling Relationship between Urban Land and Carbon Emissions: A Case Study of Chongqing, China

Exploring the coupling relationship between urban land and carbon emissions (CE) is one of the important premises for coordinating the urban development and the ecological environment. Due to the influence of the scale effect, a systematic evaluation of the CE at different scales will help to develop more reasonable strategies for low-carbon urban planning. However, corresponding studies are still lacking. Hence, two administrative scales (e.g., region and county) in Chongqing were selected as experimental objects to compare and analyze the CE at different scales using the spatiotemporal coupling and coupling coordination models. The results show that urban land and carbon emissions presented a significant growth trend in Chongqing at different scales from 2000 to 2015. The strength of the spatiotemporal coupling relationship between urban land and total carbon emissions gradually increased with increasing scale. At the regional scale, the high coupling coordination between urban land and total carbon emissions was mainly concentrated in the urban functional development region. Additionally, the high coupling coordination between urban land and carbon emission intensity (OI) was still located in the counties within the metropolitan region of Chongqing, but the low OI was mainly distributed in the counties in the northeastern and southeastern regions of Chongqing at the county level. This study illustrates the multiscale trend of CE and suggests differentiated urban land and carbon emission reduction policies for controlling urban land sprawl and reducing carbon emissions.

Thermal maturity and depositional palaeoenvironments of the Cretaceous-Palaeocene source rock Taratu Formation, Great South Basin, New Zealand

Thermal maturity and palaeodepositional environment of the Taratu Formation has been studied by evaluating its geochemical properties and organic petrographical features. Geochemical properties of the Cretaceous-Palaeocene Taratu source rock that are identified through pyrolysis indicate that this formation has excellent organic matter quality, quantity and hydrocarbon generation potential. Only the Cretaceous-aged sequence from this formation is thermally mature, with Tmax values ranging from 429 °C to 459 °C, while Palaeocene samples are found to be thermally immature. Organic matter of the Taratu Formation comprises primarily of oil and gas prone kerogen type II-III and gas prone kerogen type III, which is reflected by high HI (165.0–327.5 mg HC/g TOC) and low OI (5.00–25.7 mg CO2/g TOC) values. Tissue Preservation Index (TPI) and Gelification Index (GI) indicates that the Taratu Formation was previously deposited in a limnic environment. Further assessment of the source rock's palaeodepositional environment through correlating cross-plots of various biomarker data and evaluation of organic petrography suggests that the formation was subjected to brackish water influx.

Forecasting the development of China's coal-to-liquid industry under security, economic and environmental constraints

Coal-to-liquid (CTL) technology has attracted attention in China as an alternative way to alleviate oil shortages. However, due to low profits and environmental problems, Chinese CTL policy is cautious and unstable, rendering the future development of CTL technology uncertain. Considering security, economic and environmental constraints, this study uses system dynamics models to predict the long-term development of the CTL industry in China. The results show that CTL production will steadily increase over the next few years, and a greater increase will occur after 2021. If the government will not provide support policies for CTL industry, we forecast CTL production will be 29.3 million tons by 2030. Once government actively supports CTL, its production is projected to reach 51.8 million tons, which is 45 times greater than that in 2015. When environmental issues are also considered, the production is expected to 47.3 million tons. The sensitivity analysis shows that under different refined oil prices, CTL production ranges from 29.3 to 56.3 million tons. At present, China's CTL only accounts for 0.2% of its oil consumption, and the EROI value of CTL is approximately 0.9:1. The low EROI implies little importance for CTL from a net energy perspective. Based on these research findings, this research offers some relevant policy suggestions.

The Energy-emissions Trap

The requirement to reduce emissions to avoid potentially dangerous climate change implies a dilemma for societies heavily dependent on fossil fuels. Reducing emissions will necessitate the transition from relatively high EROI dispatchable fossil fuels to a combination of relatively low EROI intermittent renewables and geographically limited non-intermittent renewables. As renewable capacity requires energy to construct there is an initial fossil fuel cost to creating new renewable capacity. An insufficiently rapid transition to renewables will imply a scenario in which it is impossible to avoid either transgressing emissions ceilings or facing energy shortages; we term this the energy-emissions trap. In this paper, we construct a mathematical model, termed EETRAP, that builds the EROI metric and the energy characteristics of renewable generation into a macroeconomic framework. EETRAP is used for simulation analysis to test how differing assumptions about the EROI of intermittent renewables will affect the time-path of renewable investment necessary to escape the energy-emissions trap. For all runs of the model, the renewable investment rate by 2050 is significantly larger than the current energy investment rate. For declining intermittent renewable EROI, the renewable investment rate crowds out other forms of investment leading to a declining economic growth rate.

Trading Momentum: How Shares and Investors Behave During Momentum Periods

In this paper we argue that momentum profits are driven by both past performance and the relative proximity to an available reference point, the 52-week high. We construct momentum-style portfolios that are driven strictly by past returns which we call ‘run’ based measures, and compare these to portfolios driven by nearness to the 52-week high, defined as ‘range’ based measures. While both run and range based construction techniques generate positive momentum profits, they appear to be driven by separate behavioural biases. Portfolios constructed on the basis of range are driven by anchoring, while those constructed based purely on past returns are driven by representativeness and the hot hand fallacy. Portfolios selected by combining run-based methods with range-based methods outperform those selected on a single metric alone.We then undertake an analysis of order imbalance in individual and institutional investors in the six months following high and low range and run variables. The results show that individuals have significantly lower OI in all but one measure supporting that prediction that individual biases cause investors to be contrarian, thus leading to observed momentum. We lastly explore limit order use by investor class and find that all groups are sensitive to the 52 week high and significantly increase their use of limit orders. While this is not the case for past returns thus suggesting limit order use is strongly related to anchoring bias.

Hydrocarbon potential, thermal maturation of the Jurassic sequences, and the genetic implication for the oil seeps in North Thrust Zone, North Iraq

The organic geochemistry is studied for the rocks of three Jurassic formations: Sargelu, Naokelekan, and Chia Gara from the north of Iraq. These rocks comprise bituminous carbonate and shale rocks. The hydrocarbon source rock potential is evaluated by using total organic carbon (TOC) and Rock-Eval Pyrolysis. The prevalence of high values of TOC (2.21–45.12 wt.%) associated with moderate to high values of HI (225–550 mg HC/g TOC), low OI (1–33 CO2/g TOC), and high S2 values (4.53–181.0) indicate very good to excellent source rock potential for these rocks with mostly type II kerogen and few mixed-type II/III kerogen of oil prone source rocks. This is supported by high values of S2/S3 ratios (>5). Tmax values range from 440 to 447 °C in agreement with the calculated R o values (0.76–0.90) infer early to peak thermally mature stage. Based on the TOC and pyrolysis data, the rocks of the three formations have indigenous hydrocarbon mature oil prone. The geochemical investigation of biomarker parameters were performed for oil samples from two oil seepages (Banik and Tawke) which are located in the same area using gas chromatography-mass spectrometry and stable carbon isotope measurements. The measured values of Pr/n-C17 for oil samples are low coupled with high values of Ph/n-C18 indicating marine organic matters with type II kerogen accumulated under marine reducing condition. The values and plots of δ13C (saturate and aromatic) also approve the prevalence of marine reducing condition. The source rocks for the oils of both seepages are interpreted to be carbonate rocks of Mesozoic age by the measured CV values which are 0.25. All these data are in consistent with marine carbonate source rocks for these oils. The paleoredox depositional environment for the source rocks is interpreted by the low value of Pr/Ph (0.74 in Banik) and high values of homohopane ratio C35S/C34S (1.21 in Banik and 1.13 in Tawke); the values of C29/C30 (norhopane/hopane >1) as well as the high sulfur content all indicate reducing condition during the deposition of the marine source rocks. The concentrations of C27, C28, and C29 reflect the prevalence of marine algal plankton organic matters. The measured Oleanane index equal zero which indicates age older than Lower Cretaceous for the source rocks. This documented by the calculated values of C28/C29 sterane ratio, and plots on Geomark Research database gives an age of Middle–Upper Jurassic for the source rocks. According to the characteristics of depositional environment of the source rocks, the paleoredox condition, and age estimation, the oils of Banik and Tawke could be derived from the rocks of Sargelu, Naokelekan, and Chia Gara Formations.

O-021 Prevention Of Bronchopulmonary Dysplasia (bpd) In Vlbw Infants With Severe Rds – A Randomised Trial Of A New Therapeutic Regimen: Abstract O-021 Table 1

Background/aims Intra-tracheal instillation of surfactant/budesonide significantly improves pulmonary status in animals. The aim is to investigate if this therapy would decrease the incidence of BPD or death. Methods and materials This randomised controlled trial comprised 265 VLBW infants who had: 1) severe radiographic RDS, 2) requirement of IMV (FIO 2 ≥ 0.5) shortly after birth: 131 received survanta (S) (100 mg/kg) and budesonide (B) (0.25 mg/kg) (S+B gr.), 134 received S only (100 mg/kg) (S gr). The sample size was determined based on the hypothesis that 60% of infants in the S group and 40% in the S+B group would die or develop BPD defined at 34 weeks postm. age. Results The S+B infant had lower tracheal aspirate interleukins 1, 6 and 8, lower OI, lower MAP in the early course of therapy, higher chance to wean to room air (p = 0.03). No significant immediate and long term adverse effects were observed. * NIH criteria Conclusions In VLBW infants with severe RDS, administration of surfactant/budesonide significantly decreases the incidence of BPD and BPD or death with no apparent adverse side effects.

Coupled Rock-Eval pyrolysis and spectrophotometry for lacustrine sedimentary dynamics: Application for West Central African rainforests (Kamalété and Nguène lakes, Gabon)

In recent years, Nguène Lake and Kamalété Lake (Gabon, West Central Africa) have been studied repeatedly, providing comprehensive reconstructions of environmental changes over the last millennia. Both lakes are in different geomorphological and environmental settings. They are therefore excellent sites to test new methodological approaches. Indeed, the sedimentary cores provide various facies, and the previous studies provide references for calibrating the results of new methods. In this methodological issue, the present study aims to evaluate the potential of spectrophotometric and Rock-Eval coupled analysis to describe the Holocene lake and marsh deposits from tropical moist forests. This assessment is carried out on samples taken from two well-documented reference cores. The spectrophotometric analysis provides reproducible colour measurements, which inform about the nature of the main colour-bearing constituents. Coupled with Rock-Eval pyrolysis, this technique can be used to describe lithological changes and identify the probable source of sedimentary organic matter. In the studied cases, this approach identified the facies dominated by detrital terrigenous inputs (‘iron bearing’ signature and high OI values) and those associated with a more abundant primary production (‘chlorophyll’ signature, low OI and high HI), providing a distinction between palustrine and lacustrine dynamics. However, although the facies are comparable, sedimentary dynamics and sediment sources may vary depending on geomorphological and climatic contexts.

A Review of Large-Scale Man-Made River and Stream Diversions in the Humberhead Region

Geological evidence shows that many Humberhead rivers and streams have been widely diverted artificially from their original natural courses, initiated about 10,600±1,100 years ago. Unfortunately, geology cannot date these course changes. Some such courses already existed by the 1570s, being shown on Saxton’s relevant county maps. No dates of their construction are recorded but some idea of their antiquity can be gleaned from the earliest references to their existence. Certain diverted courses pre-date the 1086 Domesday Survey (one being mentioned in a charter of 959). They suggest a Roman origin, possibly as part of an inland waterways system (and locally for building-stone transport). Other diverted courses, post-Domesday but pre-Saxton, may have been constructed at varying times and for more diverse purposes such as bulk transport (e.g. of building stone and peat), drainage, powering watermills and marking boundaries. The more recent major man-made diversions, those resulting from the Vermuyden Drainage and Wentworth Judgement in the 1620s and 1630s, are well documented in historical texts and maps, so only a short summary is included here.‘for here we may read the last page of the earth’s story, where geology merges into history’ H.Franklin Parsons. 1878. The alluvial strata of the lower Ouse valley. Proceedings of the Yorkshire Geological and Polytechnic Society, volume 6, p. 214.

New chronometric data from Ifri n’Ammar (Morocco) and the chronostratigraphy of the Middle Palaeolithic in the Western Maghreb

In addition to South Africa, the Northwestern corner of the African continent is providing a wealth of data for the understanding of the behaviour of early modern humans. In NW Africa, this modern behaviour is associated with a technocomplex called ‘Aterian’. However, its definition as well as chronological position is heavily debated. As a common notion, the ‘Aterian’ is placed as the (more or less) last technocomplex of the Middle Stone Age/Middle Palaeolithic. However, the stratigraphy of the Moroccan site of Ifri n’Ammar provides evidence that the ‘Aterian’ cannot serve as a chronostratigraphic entity because of its presence in a stratigraphical sequence before as well as after Middle Palaeolithic industries lacking tanged tools. These should supposedly all occur beneath any layer containing tanged lithic objects, which are, at present, the main criteria for assigning an assemblage to the ‘Aterian’. According to the sequence of Ifri n’Ammar, the relative chronostratigraphical position of tanged tools is therefore shown not to be a single unit. Thermoluminescence (TL) dating of heated artefacts from the main layers of Ifri n’Ammar provides a first chronostratigraphic backbone for the site and for the Maghreb. Layer ‘Upper OS’, which contains tanged items as well as personal ornaments is dated to 83.3 ± 5.6 ka ( n = 10), while the underlying ‘Lower OS’, which is lacking tanged pieces, is dated to 130.0 ± 7.8 ka ( n = 9). The following layer (Upper OI), which again contains tanged items, and thus provides the earliest appearance of the technique of tanging is dated to 145 ± 9 ka. The base of the sequence is formed by a Middle Palaeolithic layer (Lower OI) again lacking tanged objects and dated to 171 ± 12 ka by TL on heated lithic artefacts. These data significantly push back in time the earliest occurrence of tanged tools and the sequence calls for a complete revision of the Maghreb chronostratigraphy.

Use of inhaled nitric oxide in the new born period: results from the European inhaled nitric oxide registry

The aim of this study was to present data relating to the use of inhaled nitric oxide (iNO) in newborn infants included in the European Inhaled Nitric Oxide Registry. Demographic, clinical and therapeutic data from seven European centres are reported. Univariate analyses were performed to identify factors associated with acute response to iNO and survival without extra corporeal membrane oxygenation (ECMO). A total of 112 newborn infants received iNO, with 40% being less than 34 weeks gestational age. The commonest indication for iNO was secondary pulmonary hypertension. Acute response to iNO was more common in infants with a higher oxygenation index (median OI 32.7 vs 22.6, p = 0.040), although acute response did not predict survival without ECMO. Infants who survived without ECMO had a lower OI prior to therapy (median OI 24 vs 43, p = 0.009), were commenced on a higher starting dose (median dose 20 ppm vs 10 ppm p = 0.013) and received a lower maintenance dose (median dose 10 vs 17 ppm, p = 0.027) than those who died or received ECMO. Collating and reporting data about iNO therapy in neonates across a number of European centres using a web-based system is feasible. These data may be used to monitor the clinical use of iNO, identify adverse effects, generate research hypotheses and promote high standards in the clinical use of iNO.

SU‐GG‐T‐485: Comparison of Rush University In‐House Dose Optimizer and Nucletron IPSA

Purpose: We quantitatively compared the Rush University In‐house Optimizer (RUIDO) with the Inverse Planning with Simulated Annealing (IPSA) used in Nucletron Plato Treatment Planning System. Method and Materials: RUIDO uses Adaptive Simulated Annealing (ASA) optimization algorithm, which is capable of optimizing a plan based on either physical dose, EUD, or TCP/NTCP. In this study, only physical dose optimization is compared. Three Syed implant HDR cases were planned using both RUIDO and IPSA. For each case, the number and positions of the catheters remain the same, and dwell time for each source position is optimized. Based on the Dose‐Volume‐Histogram (DVH) from both optimized plans, detailed comparison of coverage (CI), homogeneity (HI), and overdose (OI), etc. were performed. The source strengths in RUIDO plans were scaled to provide similar CI as the corresponding IPSA plan during plan comparison. Results: For all three cases, the normalized RUIDO plans show similar CI (within 0.1%) as the IPSA plans. In two cases, RUIDO plans appear better with higher HI (9% and 16%) and lower OI (16% and 45%). In the third case, two plans were tied, as RUIDO plan shows preferable HI (13% higher) but less preferable OI (12% lower). In addition, for all three cases, mean dose in both plans agree within 7%. It takes 10–15 seconds for IPSA to optimize the plan once. However, it might take several more trials for the user to obtain the optimal set of parameters depending on the user's experience. RUIDO plan, on the other hand, can generate the optimized plan within minutes (1–16 minutes), but it only takes one trial to do this hence needs possible shorter overall planning time. Conclusion: RUIDO is able to provide equivalent plan with possible shorter overall planning time compared with IPSA and is less user‐dependent.Partially funded by Varian Medical Systems.

Runoff and tidal influences on the estuarine turbidity maximum of a highly turbid system: The upper Humber and Ouse Estuary, UK

Results are presented from longitudinal and vertical measurements of salinity and turbidity made at spring and neap tides throughout the length of the upper Humber and Ouse Estuary, UK, during a 1-year period that experienced strong freshwater runoff during winter and a long period of very low runoff during summer. These data were complemented by tidal-cycle profiling measurements at a site in the lower Ouse. Despite the strong suspended particulate matter (SPM) stratification, salinity was fairly well mixed vertically except in the presence of high concentration, near-bed muddy layers. The data consistently exhibited a strong estuarine turbidity maximum (ETM) in the low salinity reaches of the estuary. The geographical positions of the freshwater–saltwater interface (FSI), X S, and the up-estuary intrusion of the ETM (the ETM nose, X P) measured from the tidal limit, exhibited a pronounced seasonal cycle. A multiple regression for X P in terms of the monthly-averaged runoff, Q 31 (averaged over 31 days preceding the survey) and the tidal range for the surveyed tide, TR, ‘explained’ 97% of the variance in X P. The ETM nose was located in the lower estuary during high runoff winter conditions, more than 50 km from the tidal limit, and in the upper estuary during very low runoff summer conditions, within 2 km of the tidal limit. According to the regression, the ETM nose was shifted up-estuary by 15 km between mean neap tides and mean spring tides. The location of the FSI also depended strongly on runoff. The regression for X S in terms of TR and Q 31 explained 88% of the variance. The FSI was located in the lower estuary during winter conditions and in the upper estuary during summer conditions and according to the regression there was an up-estuary displacement of 6 km between mean neap tides and mean spring tides. The separation between the ETM nose and FSI, ( X P − X S), tended to be positive (ETM nose down-estuary of the FSI) when the nose was located more than about 55 km down-estuary from the tidal limit, but was otherwise negative (ETM nose up-estuary of the FSI). When the nose was located within about 30 km of the tidal limit, it tended also to be about 10–30 km up-estuary of the FSI. A multiple regression of ( X P − X S) in terms of X P and TR explained 78% of the variance. The magnitude of the maximum, depth-averaged SPM concentration within the ETM, P, was most closely related to the location of the ETM nose. The logarithm of P decreased approximately linearly with X P and P was reduced from 35 g l − 1 during summer, when X P was less than 2 km, to 3.5 g l − 1 when X P was 58 km. A regression explained 94% of the variance. Tidal-cycle profiling illustrated the seasonal ETM movements via the presence of very high turbidity waters in the lower estuary at high water during winter and spring, at low water during summer and early autumn and at mid-ebb through to mid-flood in the late autumn. This seasonal movement of the ETM also was accompanied by a seasonal variability in sand-sized subtidal and intertidal bed-sediment distributions within the upper Humber and Ouse Estuary in which very fine sand was transported down-estuary over the high runoff winter period.

425 Early Endotracheal Instillation of Budesonide (B) Using Surfactant (SF) as a Vehicle to Preterm Infants at Risk for CLD¢WA Pilot Study

Budesonide (B) undergoes an extensive biotransformation during the first pass metabolism in the liver to metabolites of low glucocorticoid activity. Surfactant (SF) (Survanta) can be used as a vehicle for B delivery in ventilated rabbits. Our previous study indicated that the addition of B to survanta (with ratio< =1:50) would not affect the surface tension property of surfactant. We therefore hypothesize that direct endotracheal installation of B and survanta would effectively deliver B into the lungs and would provide strong local anti-inflammation without much systemic side effects.Thirty-two infants (< = 1500 gm) with severe RDS who required IMV shortly after birth were randomly assigned into 2 groups: Gr. I (16) received SF (100 mg/kg) and B (0.5 mg or 2 ml/kg) and Gr. II (16) received SF (100 ml/kg) and saline (2 ml/kg). CLD was judged at 36 wks postconp. age. All infants were followed a standard protocol for resp. care.The two groups were comparable in BW, GA, perinatal characteristics and cardiopulmonary status on admission to NICU. Infants in Gr. I had significantly (P<0.05) higher PaO2 and lower OI on day 2, 3 and required less need of CPAP than Gr. II (mean ¡Ó S.D.; PO2 63 ¡Ó 25 vs 47 ¡Ó 18 mmHg and 62 ¡Ó 9 vs 43 ¡Ó 4 mmHg; OI 3.8 ¡Ó 0.7 vs 7.2 ¡Ó 2.4 and 3.6 ¡Ó 0.9 vs 6.3 ¡Ó 1.9; CPAP 2/16 vs 5/16). The incidence of CLD tends to be lower in Gr. I than Gr. II (4/16 vs 8/16). The two grs. were comparable in mortality (5/16 vs 4/16), in physical growth (BW, HL and HC), in blood pressure and serum glucose and in doses of surfactant administered (mean 1.8 vs 2.6 doses). We concluded that endotracheal instillation of surfactant + Budesonide improved pulmonary status without immediate side effects. This therapeutic regimen is warranted for further study.

Hydrological Monitoring of an Alluviated Landscape in the Lower Great Ouse Valley at Over, Cambridgeshire: Results of the Gravel Extraction Phase

Hydrological Monitoring of an Alluviated Landscape in the Lower Great Ouse Valley at Over, Cambridgeshire: Results of the Gravel Extraction Phase

Suspended sediment fluxes in the tidal Ouse, UK

A strong turbidity maximum (TM) of suspended particulate matter (SPM) was observed in the upper Humber and lower Ouse during both spring and neap tides of May 1994. Near-bed concentrations within the TM sometimes exceeded fluid mud levels following slack water periods. SPM within the TM comprised very fine-grained material. Its low organic content demonstrated that the SPM was essentially mineral, clastic sediment. Generally, tidal advection of SPM was the dominant flux mechanism and the pronounced flood-ebb asymmetry in the tidal currents was reflected in these fluxes. However, the presence of fluid mud near the down-estuary margins of the TM on the early ebb resulted in a strong, up-estuary shear flux that opposed the ebb-directed advection. This mechanism therefore acted to maintain fine sediment in the TM region. SPM concentrations in the inflowing fresh water at Naburn Weir were much less than those observed within the TM region ( 70 000 mg l -1 ). The estimated mean SPM transport into the tidal Ouse across Naburn Weir was about 4 kg s -1 (>2 and <11 kg s -1 ) during 1994. In the TM area, the SPM transported during the course of a single spring tide flood was roughly equivalent to 30 months of Naburn SPM inflows at average 1994 levels. The tidally averaged SPM transport in the TM region was directed into the estuary and, per tide, was roughly equivalent to three months of Naburn inputs.

Role of Oxygen in the Limitation and Inhibition of Nitrogenase Activity and Respiration Rate in Individual Soybean Nodules.

Although infected cell O2 concentration (Oi) is known to limit respiration and nitrogenase activity in legume nodules, techniques have not been available to measure both processes simultaneously in an individual legume nodule. Consequently, details of the relationship between nitrogenase activity and Oi are not fully appreciated. For the present study, a probe was designed that allowed open circuit measurements of H2 evolution (nitrogenase activity) and CO2 evolution (respiration rate) in a single attached soybean nodule while simultaneously monitoring fractional oxygenation of leghemoglobin (and thereby Oi) with a nodule oximeter. Compared to measurements of whole nodulated roots, use of the probe led to inhibition of nitrogenase activity in the single nodules. During oximetry measurements, total nitrogenase activity (TNA; peak H2 evolution in Ar/O2) in the single nodules was 16% of that in whole nodulated roots and 48% of nodulated root activity when Oi was not being measured simultaneously. This inhibition did not affect the nodules' ability to regulate Oi, because exposure to Ar/O2 (80:20, v/v) caused nitrogenase activity and respiration rate to decline, and this decline was linearly correlated with a concurrent decrease in Oi. When the nodules were subsequently exposed to a linear increase in external pO2 from 20 to 100% O2 at 2.7% O2/min, fractional leghemoglobin oxygenation first increased gradually and then more rapidly, reaching saturation at a pO2 between 76 and 100% O2. Plots of nitrogenase activity and respiration rate against Oi showed that rates increased with Oi up to a value of 57 nM, with half-maximal rates being attained at Oi values between 10 and 14 nM O2. The maximum nitrogenase activity achieved during the increase in pO2 (potential nitrogenase activity) was 30 to 57% of that measured in intact nodulated roots, showing that O2 limitation of nitrogenase activity could account for a significant proportion of the inhibition of TNA associated with the use of the probe. However, some factor(s) in addition to O2 must have limited the activity of single nodules at both subsaturating and saturating Oi. At Oi values greater than about 57 nM, nitrogenase activity and nodule respiration were inhibited, but, because this inhibition has been shown previously to be readily reversible when the Oi was lowered, it was not attributed to direct O2 inactivation of the nitrogenase protein. These results indicate that maximum nitrogenase activity in legume nodules is supported by a narrow range of Oi values. Possible biochemical mechanisms are discussed for both O2 limitation of nitrogenase activity at low Oi and inhibition of nitrogenase activity at high Oi.

Pollen Analytical Evidence Relating to the Vegetation History of the Chalk

Pollen data are presented showing that the Chalk Downs around the Lower Ouse Valley in Sussex were well wooded from the early post-glacial until the Middle Bronze Age, c. 1240 bc, and that even then grassland was not the dominant vegetation type. There is also evidence that the downland soils were deeper and probably less calcareous in the early post-glacial. A pattern of temporary vegetation clearances and soil erosion in the Neolithic followed by more permanent effects in the Middle Bronze Age is in agreement with several pieces of evidence from elsewhere in south-east England, but contrasts with the clearance of the central southern Chalk by the Neolithic. Ulmus and Tilia were particularly affected by human activities, and the hypothesis is put forward that they were selectively cleared from the most mesic, base-rich valley soils. Evidence is also given for the post-glacial history of Fagus in the region.

Histochemical studies on the architecture of rat temporal muscle

The histochemical organization observed in sections of the temporal muscle of adult malerats was investigated by a succinicdehydrogenase staining (SDH) method. Three distinct muscle fibertypes were also distinguished in the temporal muscle. Significant differences in the average OI and SI values were found in different regions (from origin to insertion), and in different parts (the anteriortemporal, posterior temporal and deep temporal muscle). Moreover, differences were found in thepercentage distributions of OI and SI of different primary fasciculi in each of the temporal muscle. Ingeneral, the average OI and SI values were highest in the deep temporalis, intermediate in the anteriortemporalis and lowest in the posterior temporalis. In aging rats the three types of muscle fibers wereeasily identified, and differences in the average OI and SI values in different muscle parts were foundto be greater. In addition, primary fasciculi with high OI and SI values or those with low OI and SIvalues were more numerous than in young adult rats.