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A series of low‐density polyethylene (LDPE) surfaces, chemically modified using a number of oxidative techniques employed for adhesion enhancement (pretreatments), have been studied by time‐of‐flight (ToF) SIMS and XPS. The methods consisted of corona discharge, flame, electrochemical, chromic acid, acid dichromate and acid permanganate treatment. All except flame treatment were performed under mild and fairly severe conditions to yield a range of surface chemistries. The XPS analysis, using high energy resolution and a refined approach to C 1s curve‐fitting, provided some new insights into the quantitative assessment of the type and concentration of functional groups. Both positive and negative ion ToF‐SIMS spectra were obtained at high mass resolution. The oxygen‐containing fragments were identified by accurate mass analysis and subjected to a detailed comparison with the XPS results. No convincing relative intensity correlations could be identified that would allow particular secondary ion fragments to be associated strongly with particular functional groups (in this multi‐functional surface situation). Inorganic residues resulting from wet chemical treatments were also investigated and here the two techniques were found to be more complementary. Copyright © 2003 John Wiley & Sons, Ltd.

Focuses on the dating of diagenesis by exploiting trace of uranium within monazite structure in Pre-Mesozoic mudrock successions from the Caerau Formation of central Wales. Reasons for the difficulty of providing radiometric dates for diagenetic mineral formation within sedimentary to low-grade successions; Stratigraphy and lithology of the monazite structure; Method used in extracting monazites; Analysis of the monazite structures.

Attempts to improve the performance of water treatment works through the application of improved control and measurement have had variable success. The most quoted reason for this is that the individual dynamic operations defming the treatment cycle are complex, highly non-linear and poorly understood. These problems are compounded by the use of faulty or badly maintained sensors. The efficient and robust operation of any industrial system is critically dependent on the quality of the measurements made. Also, the structure of the control policy and choice of the individual controller parameters are important decisions to the economic operation.Because of their ability to capture non-linear information very efficiently, artificial neural networks (ANNs) have found great popularity amongst the 'control community' and other disciplines. This paper discusses a recent application of ANNs at surface water treatment works. The study is used to describe how the introduction of ANNs has resulted in more reliable system measurement and consequently improved coagulation control

Time‐of‐flight SIMS has been used to identify chemical changes caused to hexatriacontane and various hydrocarbon polymers after electrochemical treatment with nitric acid either alone or in the presence of silver ions. The spectra of polypropylene and high‐density polyethylene treated in the presence of Ag2+ions indicated the presence of hydroxyl, carbonyl and carboxyl groups. With polystyrene, attack at both the polymer backbone and the ring occurred. A styrene– butadiene– styrene (SBS) block copolymer was the most extensively modified, with preferential attack of the butadiene. Nitrate ester groups were detected in all cases but the concentration was much higher for SBS than for the other polymers. Oxidation of hexatriacontane was confirmed for the first time. In the absence of silver ions the modification was chemically similar for all polymers but to a lesser extent, except in the case of SBS. Copyright © 2000 John Wiley & Sons, Ltd.

Pyroxene granulites and charnockites are associated with metasedimentary khondalite (garnet-sillimanite gneiss) and migmatites in the Eastern Ghats mobile belt. Various stages of in situ granulitization similar to those observed in southern India and Sri Lanka are present. Geochemically the granulite suite around Visakhapatnam is bimodal, with acid and mafic variants. There is an increase in the concentration and fractionation of the rare earth elements (REE) from pyroxene granulites to charnockites, and six Sm-Nd models ages ($$T_{DM}$$) range from 2.86 to 2.35 Ga, with 2.1 Ga for a younger granite. The charnockites, a pyroxene granulite, and granite define a Pb/Pb isochron age of $$1176 \pm 201 Ma$$. U-Pb ages of zircons and monazites from a charnockite near Phulbani, Orissa, yield near concordant data with ages of $$985 \pm 5 Ma$$and $$965 \pm 7 Ma$$, respectively. The new isotopic data and the available ages from the northeastern part of the Eastern Ghats in Orissa suggest a major charnockite formation event between ca. 1170 and 950 Ma. This event is contemporaneous with that of Sri Lanka but much younger than the late Archean granulite event in southern India.

Precise Pb isotopic data are reported for 19 galenas and 2 other minerals from the Archaean Pilbara District of Western Australia. Repeated measurements on the Broken Hill Standard Ore show good agreement with published calibrations from two other laboratories, and an overall 95 percent confidence level within ±0.05 percent per mass unit, whether fractionation correction is by the double-spike procedure or by use of a simple mass-dependent factor. Two stratiform deposits yield the most primitive ratios (206Pb/204Pb=11.89; 207Pb/204Pb=13.69; 208Pb/204Pb=31.79) and model ages in good agreement with the 3.45 Ga age on zircons from volcanics correlatable with the host-rocks. Other minor galena occurrences, with quartz-vein association, appear to be younger, with position along the growth curve surprisingly consistent with the age sequence predicted from field observation. The data also extend the time-range of previously-reported trends in ‘apparent U/Pb’ of the conceptual Pb source, and reveal new features of the corresponding Th/U systematics: a generally-observable trend in the Archaean of Australia, Southern Africa and West Greenland is that the ‘source Th/U’ seems significantly higher than is allowed for in any of the current Pb-growth models. In detail, the sample-sample variations in indicated source parameters are in many cases correlatable with the nature of the neighbouring rocks and emphasise that, whereas Pb isotope rations in the galenas of huge deposits may well serve as a convenient sampler of overall trends in the Earth's crust, subeconomic occurrences such as these may reveal valuable information about local variations in U-Th-Pb distribution.

The dominantly quartzitic Mt Narryer sedimentary sequence is chemically diverse, consistent with deposition in a high-energy continental environment. The dominant sediment source was stable continental crust with crustal residence ages (Sm-Nd TDM) of 3.3-3.8 Ga. This hinterland had 'typical post-Archaean' characteristics such as negative Eu anomalies which were probably generated prior to 3.3 Ga. The succession has higher Sm/Nd than is common for younger sedimentary sequences, suggesting a higher proportion of mafic or anorthositic crust than is seen in the present outcrop around Mt Narryer. Internal Sm-Nd isochrons for two samples confirm the timing of upper amphibolite-granulite facies metamorphism at 2700 ± 100 Ma, probably ca 400 Ma after deposition.The small sedimentary unit which has given published detrital zircon ages >4 Ga is an atypical member of the sequence. It has high 147Sm/144Nd (0.145) and the TDM = 4.5 Ga is therefore equivocal, but it supports the view that remnants of >4 Ga crust existed when the Mt Narryer sedimentary sequence was deposited.

Using time-of-flight and laser-induced fluorescence methods, the efficiencies of rotational and vibrational relaxation of BrCl by Cl2 have been studied by measuring the final translational, rotational and vibrational temperatures of a supersonic beam of BrCl seeded in Cl2. Collision numbers, ZR ∼ and Zv ∼ 28, have been obtained. Rotational relaxation is found to occur at a rate close to gas kinetic. Vibrational relaxation appears to be very efficient at the low temperatures of the beam and this is attributed to additional relaxation being achieved due to the formation of metastable orbiting complexes.

Three breeds of Javanese sheep are described briefly and data suggesting the segregation of a gene with large effect on ovulation rate and litter size are presented. The three breeds are Javanese Thin Tail (JTT), Javanese Fat Tail (JFT) and Semarang (SEM), the last possibly a substrain of JTT. All three breeds have mean mature ewe weights under 30 kg. Ovulation rate and litter size did not differ significantly among the three; all had litter sizes of up to 4 or 5 with a mean for mature ewes of approximately 2. Ovulation rate ranged from 1 to 5 and had an average within-breed repeatability of .8 within season and .65 between seasons. Within-breed repeatability of litter size was .35 ± .06. Prenatal survival in pregnant ewes with two, three and four or more ovulations averaged 93, 88 and 86% over two seasons. Dams that had at least one ovulation rate or litter size record ≥ 3 produced two groups of daughters in approximately equal numbers: one group with many records ≥ 3 and mean ovulation rate and litter size of 2.73 and 2.31, respectively, and one group with ovulation rates and litter sizes of 1 or 2 and corresponding means of 1.39 and 1.38. Dams with ovulation rate or litter size records of only 1 or 2 produced daughters in which over 90% had records of only 1 or 2. Estimated heritabilities for the mean of approximately three ovulation rate or litter size records from these daughter-dam comparisons exceeded .7. These results suggest segregation of a Booroola-type gene, one copy of which increases ovulation rate by about 1.3 and litter size by .9 to 1.0. Relationships between duration of estrus and ovulation rate, and between timing of release of luteinizing hormone and number of eggs shed, resemble the pattern in Booroola Merino more closely than that in Finnish Landrace or Romanov, supporting the hypothesis of a major gene.

Changes in the SIMS spectra of poly(vinyl chloride) (PVC) and poly(methyl methacrylate) (PMMA) as a function of 8 keV Cs+dose have been studied in the range 1011–5×1013ions cm‐2. In order to resolve uncertainties in previous studies (based on quadrupole SIMS and insulating samples) this work has utilized a high mass resolution ToF‐SIMS instrument and films on silicon sufficiently thin to obviate the need for surface potential control (charge neutralization). The form of the damage curves has been compared with a recently introduced model of damage development based on the statistics of bond breaking. © 1997 by John Wiley & Sons, Ltd.

A large number of design strategies exist for multivariable control situations. Many of' the methods require a linear time-invariant process characterisation in the form of a state space model or transfer function matrix description. Quite often this is not available and could be evpensive to realise. If this latter route is pursued there needs to be considerable benefits in the quality of the resulting closed-loop performance, especially when compared to those methods which only require minimal system information. The main aim of this paper is to compare a range of multivariable design strategies using a commercial multivariable coupled tank experimental rig as the uncompensated plant,

A kinetic study of electronically excited oxygen atoms, O(21D2), is presented. These optically metastable species were generated by repetitive pulsed irradiation in the Hartley-band continuum and monitored photoelectrically in absorption by time-resolved attenuation of resonance radiation at λ = 115.2 nm (O(31D20)←O(21D2). Absolute rate constants for the collisional quenching of O(21D2) are reported for the gases NH3, H2O2, C2H6C3H8, and C(CH3)4. These are found to be respectively (in units of 10−10 cm3molecule−1S−1at 300 K), 6.3 ± 0.7, 5.2 ± 0.6, 7.3 ± 0.8, 9.5 ± 1.0, and 12.3 ± 1.3. With the exception of a recent measurement for NH3•these data represent the first absolute measurements for these quenching gases. Further, a general comparison is made between absolute rate measurements using this technique and recent work by Schiff and co-workers using time-resolved emission at λ = 630 nm (O(21D2) → O(23P2)) in order to monitor the excited atoms.

The extent to which ewe reproduction could be improved by supplementary feeding around lambing time was investigated with four groups each of 16 ewes which were run continuously with fertile rams until they had lambed three times. One group was fed at a maintenance level throughout and the other three groups were given supplementary feed during the last four week of each pregnancy only, or during the last four weeks of pregnancy plus the first six weeks after each lambing, or during the last four weeks of pregnancy plus the first 12 weeks after each lambing. The average body weight of lambs weaned at 13 weeks of age increased (P<0.001) progressively from 6.0 to 9.1 kg with increasing duration of supplementary feeding. There were however no significant differences between treatment groups in mean interval between successive lambings (202 days), ovulation rate (2.26), litter size (1.58), lamb birth weight (1.8kg), preweaning lamb mortality (37%) or number of lambs weaned per lambing (0.99).

New Rb-Sr, Sm-Nd and Pb-Pb data are presented from banded gneisses in the Mt Narryer region of the Western Gneiss Terrain, together with Rb-Sr and Sm-Nd data from cross-cutting granite sheets. The Meeberrie Gneiss, which previously gave a Rb-Sr isochron age of 3348 + 43 Ma and an initial ratio of 0.7037 + 0.0005, has given a Pb-Pb age of 3357 ± 70 Ma, whilst an additional suite of the same gneisses collected to the SW of the original samples gives a Rb-Sr age of c. 3100 Ma with an initial ratio of c. 0.705. Deformed sheets of recrystallized granite which intrude the Meeberrie Gneiss give a Rb-Sr age of 2579 + 122 Ma with an initial ratio of 0.7143 ± 0.0092. Sm-Nd analyses on samples of the Meeberrie Gneiss give TCHUR ages of 3710 ±30 Ma and 3620 + 40 Ma, which support the previously determined model age of 3630 ± 40 Ma. An additional TCHUR of 3540 ± 30 Ma for a sheet of Dugel Gneiss within the Meeberrie Gneiss coincides with a previously reported value of 3510 ± 50 Ma for another sample of the Dugel Gneiss. Two cross-cutting granite sheets give TCHUR ages of 3120 ± 30 Ma and 3070 ± 40 Ma. The geochronological data in this paper support and extend the isotopic evidence previously reported from the banded gneisses of the Mt Narryer region, and confirm that the Western Gneiss Terrain is the oldest known major segment of sialic crust in the Yilgarn Block, Western Australia.

Time-of-flight and laser-induced fluorescence methods have been employed to study the rotational relaxation of SO2 by various gases from measurement of the terminal translational and rotational temperatures for SO2 in various seeded supersonic molecular beams. Rotational collision numbers for the relaxation of SO2 by various gases have been obtained for the first time; the only previous determination was for rotational self-relaxation of SO2 by thermal conductivity measurements. It is found that in all cases the efficiency of rotational relaxation increases with increasing temperature.

The wilderness travel simulation model estimates complex recreation use patterns in park and wilderness environments. The model was applied to a section of the Appalachian Trail in Vermont, a linear, long-distance, multiple-access trail system characteristic of the eastern United States. Many portions of the trail, including the study area, are now experiencing high use. The model estimated the average number of trail encounters per party day to be 3.3 and the average number of camp encounters per party night to be 2.3. Other measures of recreation use were also estimated that should prove useful to trail management and administration. Three trail management scenarios were tested, providing several preliminary insights to managers: the desirability of use redistributions as opposed to across-the-board reductions and needed emphasis on spatial use patterns and campsite encounters. Only minor modifications to the program were needed in applying the model to the trail environment and the model functioned accurately according to the validity tests performed.

A novel system of non-symmetric dimers containing 4-n-alkyloxy-substituted cinnamic acid and cyanobiphenyl groups has been studied. Two series were prepared: in one the flexible spacer was varied in length while the spacer was fixed. The spacer length has a profound influence on the nematic-isotropic transition temperature of these materials and a large odd-even effect is observed for the series. The terminal chain also plays a significant role in determining the liquid crystal phase behaviour: a smectic A phase is exhibited for the ethyl and propyl homologues, in addition to a nematic phase; this smectic phase vanishes for intermediate chain lengths but then reappears for the nonyl and decyl members of the series. X-ray diffraction has revealed the structure of the smectic A phase for the ethyl homologue to be intercalated, whereas that for the decyl compound is interdigitated. The existence of the intercalated smectic A phase has previously been explained in terms of a charge-transfer interaction between unlike mesogenic groups. However, for the non-symmetric liquid crystal dimers described here this specific interaction appears unlikely and we discuss, therefore, other possible mechanisms for the formation of intercalated smectic phases.

The dynamics of the hydrogen atom abstraction reactions of O(3P) with cyclohexane, cyclohexene and 1,4-cyclohexadiene have been investigated by measuring the OH product internal state distributions by laser-induced fluorescence under crossed-molecular beam conditions. The rotational state distributions are similar for all three reactions and show that a low fraction (1-3 per cent) of the available energy goes into OH rotation. This indicates that abstraction is a direct reaction and only takes place when the O atom is collinear with the C-H bond under attack. The amount of OH vibrational excitation increases only modestly (16-22 per cent) despite a large increase in the exoergicity along the series of reactions. Comparison with the predictions of a three-body model suggests that not all of the increased exoergicity due to the stabilization energy of the hydrocarbon radical product for the reactions with the unsaturated alicyclic hydrocarbons is available for vibrational excitation of the OH and that some internal excitation of the radical takes place.

Changes in the SIMS spectra of poly(vinyl chloride) (PVC) and poly(methyl methacrylate) (PMMA) as a function of 8 keV Cs⁺ dose have been studied in the range 10¹¹–5×10¹³ ions cm^-2. In order to resolve uncertainties in previous studies (based on quadrupole SIMS and insulating samples) this work has utilized a high mass resolution ToF-SIMS instrument and films on silicon sufficiently thin to obviate the need for surface potential control (charge neutralization). The form of the damage curves has been compared with a recently introduced model of damage development based on the statistics of bond breaking. © 1997 by John Wiley & Sons, Ltd.

Summary.Peripheral plasma concentrations of LH, oestradiol-17β and progesterone were measured in 13 mature swamp buffalo cows at 4-h intervals from 36–40 h before until 36–40 h after the onset of oestrus. Mean LH concentrations increased sharply to a peak of 35 ng/ml and returned to basal levels of 5 ng/ml within a 12-h period beginning soon after the onset of oestrus. Mean oestradiol-17β concentrations were within the range 9–13 pg/ml from 36–40 h before until 12–16 h after the onset of oestrus, and within the range 7–9 pg/ml thereafter. Progesterone concentrations remained around 0·1 ng/ml throughout the sampling period. There were no significant differences in hormone concentrations or changes between cows that conceived and those that did not conceive to artificial insemination 12–24 h after onset of oestrus.

This paper continues a survey of Sm-Nd age relationships at the margins of the Yilgarn Block, Australia's largest Archaean craton. Model ages have been determined along an irregular transect extending approximately 120 km from the extreme SW of the Western Gneiss Terrain of the Yilgarn Block through the western extremity of the Albany-Fraser Province, a major Proterozoic mobile belt. The ages demonstrate the significance of the Manjimup and Pemberton Lineaments as major crustal discontinuities. The sequence of ages across the lineaments strongly supports accretionary models of Precambrian crustal evolution, although some aspects of the age sequence can also be interpreted as mixing trends. Within the Western Gneiss Terrain, the Manjimup Lineament marks a change from older (c. 3.1 Ga) to younger (c. 2.7 Ga) Archaean gneisses. Further south the Pemberton Lineament, marking the northern tectonic boundary of the Albany-Fraser Province, defines a change from Archaean (c. 2.7 Ga) to Proterozoic (c. 2.1 Ga) mantle differentiation ages. The one exception within the mobile belt is a sample of granulite from Windy Harbour, the age of which (3.1 Ga) implies that the Proterozoic crustal material of the Albany-Fraser Province is sharply terminated to the west as well as to the north. The ages determined within the Albany-Fraser Province, together with those previously reported for the Gascoyne Province, point to the existence of a major crust-forming event surrounding a considerable portion of the Yilgarn Block about 2 Ga ago.

Earlier studies of the nature and extent of Proterozoic activity around the Archaean Yilgarn Block, based on Sm-Nd model ages, have now been extended by an examination of the western margin. New data from the western Yilgarn Block indicate that rocks of the Chittering Metamorphic Belt (2.8-2.9 Ga) are significantly younger than rocks in the other three metamorphic belts of the Western Gneiss Terrain (literature values ≥3.0 Ga). This suggests possible continental growth by marginal accretion during the Archaean. Data from Yilgarn Block granitoids indicate a complex and extended period of generation, ranging from 2.7 to 3.1 Ga. There is a major time break at the western margin of the Yilgarn Block, marked by the Darling Fault. All rocks sampled W of the fault have Proterozoic model ages. This confirms the existence of a Proterozoic mobile belt along the western edge of the Yilgarn Block and provides further evidence that the present Darling Fault follows a zone of Precambrian crustal discontinuity. The remarkably consistent age of 1.8 Ga for rocks occurring both within and below the Perth Basin is similar to the youngest values determined in the Gascoyne Province and western parts of the Albany-Fraser Province. This suggests contemporaneous mobile belt activity around the entire western portion of the Yilgarn Block and strongly supports models of Proterozoic continental growth by marginal accretion. Although data are limited, a further westward younging is suggested by available isotopic data from the Leeuwin Block (age ca 0.6 Ga). This suggests a further westward, step-like decrease in age away from the Archaean Yilgarn Block.

Theory predicts that a compound whose structure possesses both rod-like and disc-like characteristics should exhibit a biaxial nematic phase. With this in mind we have synthesized and characterized two new series of non-symmetric dimers containing rod-like and disc-like mesogenic units linked by a flexible spacer. The two series differ in that in one the perimeter of the disc-like unit is decorated with alkyl chains, whereas for the other it is not. The liquid crystalline properties of the two series were investigated both as pure systems and in their equimolar binary mixtures with an electron acceptor. The nematic phase formed by the equimolar binary mixtures is monotropic. However, a small entropy change at the nematic-isotropic transition could be determined. The nature and structure of the monotropic nematic phase is discussed.

The Carless Day Scheme was introduced in New Zealand to save fuel and operated from 31 July 1979 to 12 May 1980. Each private motorist selected a day of the week when his car was not to be used. Two surveys of a sample population in Christchurch gave information on travel behaviour and attitudes before the scheme began and after four months of operation.Three main adaptations were made to travel behaviour on the selected carless day: largest was the use of another car which favoured the multi-car families, followed equally by postponement of the trip to another day or by sharing a car with another person sometimes in a formal carpool but commonly on an informal basis.The Attitude Survey showed unanimity on the need to save petrol but rejected the necessity for carless days by a margin of two to one. The latter reflected the dominant attitude that the carless day scheme was unfair in that different socio-economic groups were not uniformly affected, and that the scheme was not effective in saving petrol.

Lamb production in relation to total feed consumption was recorded in Javanese thin tail (JTT) ewes and in first cross Suffolk×JTT (SX), Wiltshire Horn×JTT (WX) and Poll Dorset×JTT (DX) ewes over three successive lambings or for 21/2 years after joining with rams of the same genotypes in a continuous mating system. For the JTT, SX, WX and DX genotypes respectively, total numbers of lambs weaned per ewe joined were 3·77, 2·50, 2·08 and 1·33, mean lamb body weights at weaning were 12·8, 18·8, 18·6 and 20·9 kg, total weights of lamb weaned per ewe joined were 48·4, 46·9, 38·8 and 27·9 kg, and average weights of feed consumed by the whole production system per kg of lamb weaned were 16·4, 21·9, 23·5 and 32·8 kg. Thus cross-bred ewes required more feed to produce fewer though heavier lambs without any real increase in total productivity.

The effect of rams on the duration of oestrous behaviour was studied with oestrogen-treated spayed ewes. Different degrees of association between ewes and rams influenced the duration of oestrus in two ways.First, the duration of oestrus measured by teasing ewes with active rams once every 4 hr was shorter when ewes and rams remained together than when they were kept apart between observations. Continuous contact with rams appeared to limit the duration of oestrus by inhibiting the neural mechanism controlling the expression of oestrous behaviour.Second, the duration of oestrus measured by teasing ewes individually every 4 hr and keeping them with rams between observations was longer than that measured when ewes were kept in continuous uncontrolled association with rams. Regular teasing probably resulted in a longer duration of oestrus because it eliminated competition between ewes and rams and overcame the apparent unwillingness of rams to continue to mate with the same ewes for the full duration of their oestrus.The incidence, time of onset, and duration of oestrous behaviour all responded linearly to increasing doses of oestrogen, but the slopes of these dose-response relationships were not affected by the different methods of measuring oestrous behaviour.

The effects of dose of oestrogen and season on the expression of oestrous behaviour was studied in 60 spayed and 16 intact ewes.In progesterone-primed spayed ewes the incidence and duration of oestrous behaviour increased and the interval between injection of oestrogen, and onset of oestrous behaviour decreased as the dose of oestrogen was increased. The linear regression of duration of oestrus on log dose of injected oestrogen provided the most precise measure of the effect of changing dose level of oestrogen on oestrous behaviour.The sensitivity of spayed ewes to constant levels of oestrogen increased to a maximum near the middle of the breeding season and then declined to a minimum during the non-breeding season. In progesterone-synchronized intact ewes the interval between the end of progesterone treatment and onset of oestrus was at a minimum, and duration of oestrus at a maximum, near the middle of the breeding season. By bioassay it was estimated that endogenous oestrogen production was greater near the middle of the breeding season than at either the beginning or end.It is concluded that seasonal variation in the expression of oestrous behaviour in intact ewes is controlled by changes in both the production of endogenous oestrogen and the sensitivity of ewes to it.

“Spray Seed,” which involves direct combine-drilling of cereals after killing weeds and regenerating pasture grasses with a mixture of bipyridyl herbicides, has been developed in Western Australia as a means of minimizing the loss of grazing land during seedbed preparation at a time of the year when feed is critically short for sheep and other livestock. The results of several years’ field trials are summarized together with practical experience from a farm 120 miles north-east of Perth.

The first ovulation and first oestrus after parturition were recorded in four groups of Merino ewes which: (a) reared their lambs normally, (b) were allowed to suckle their lambs only during three 1-hr periods each day, (c) had their lambs removed on the day after birth, or (d) had their lambs removed on the day after birth and were injected intramuscularly with 5 i.u. oxytocin ten times each day for the first 17 days after parturition.Ewes with restricted suckling activity or with lambs removed on the day after birth showed their first post-partumovulation and oestrus at about the same times as ewes which reared their lambs normally.Ewes injected with oxytocin showed their first post-partumovulation and oestrus significantly earlier than ewes in the other three groups.

Both XPS and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) imaging have been used to characterize chemically micropatterned surfaces formed by plasma polymerization, using a copper transmission electron microscope grid as a mask. Micropatterns of spatially distinct regions of fluorine, carboxylic acid and hydrocarbon functionalities have been imaged by ToF‐SIMS, whereas imaging XPS has demonstrated the ability to produce patterns of nitrogen‐containing functionalities. Features as small as 50μm bars and 75μm ‘islands’ have been imaged. The utility of these chemically defined patterns has been demonstrated by the spatial binding of protein and by the attachment of cerebellar granule neurons. Copyright © 2001 John Wiley & Sons, Ltd.

The Yilgarn Block is an ancient crustal block which extends over ∼650,000km2in the south-west of Western Australia and consists of high-grade gneiss and granite–greenstone terrains1. Being one of the largest segments of Archaean crust in the world, it is important to studies of early crustal evolution. We report here a geochronological study of banded gneisses near Mount Narryer, in the north-west of the Yilgarn Block, which has given a Rb–Sr whole-rock isochron age of 3,348±43 Myr with an initial 87Sr/86Sr ratio of 0.7037±0.0005. The data indicate that the rocks had a prior crustal residence time of ∼200 Myr. The validity of this early Archaean age is supported by model Sm–Nd ages of 3,510 Myr and 3,630 Myr for two of the samples. Taken together, these ages represent the oldest evolutionary sequence so far identified in the Yilgarn Block, and are comparable with old ages from other Archaean cratons elsewhere in the world.

The letter describes a theoretical model for the prediction of BER penalty at a digital regenerator where the probability density function of the alignment jitter at the regenerator is known. A numerical integration method is used to examine cases of particular interest to systems engineers.

Seasonal variation in the incidence and duration of behavioural oestrus in spayed ewes treated with progesterone and oestrogen has been attributed to changes in the sensitivity of ewes to oestrogen (Reardon & Robinson, 1961; Fletcher & Lindsay, 1971). This interpretation is open to question, however, in view of suggestions from Lamond & Bindon (1962) and Lamond (1964) that intact ewes showed seasonal changes in sensitivity to progesterone. The investigation reported here was designed to determine whether changes in sensitivity to progesterone contributed to seasonal variation in the expression of oestrous behaviour in spayed ewes.The experiment was of factorial design with three different doses of progesterone for priming, two breeds of ewe and two seasons of observation. Sixty spayed Merino and 60 spayed Border Leicester × Merino cross-bred ewes were each allotted at random to three groups of 20. They were injected daily with 5, 10 or 20 mg progesterone

Several 9α-halogenated progestagens are of high biological activity in the ewe. Cronolone (9α-fluoro-11β-hydroxy-17α-acetoxyprogesterone), SC-21110 (9α-chloro-11β-hydroxy-17α-acetoxyprogesterone and SC-5848 (9α-chloro-11β-hydroxyprogesterone) are indistinguishable from progesterone in priming the spayed ewe to respond to oestrogen and moreover are 20 times as potent as progesterone in this bioassay (Shelton, Robinson & Holst, 1967; Holst & Moore, 1968; R. Sinclair, personal communication). Cronolone has a similar potency in the inhibition of oestrus (Shelton & Robinson, 1967), and in a flock of ewes allows precise synchronization of oestrus and ovulation after termination of treatment (Robinson, Moore, Holst & Smith, 1967). These findings indicate that 9α-halogenated progestagens are similar to progesterone in duration of activity and are of high potency. To study further the biological activity of these compounds, they were tested for ability to maintain pregnancy in rats.Virgin female rats weighing 200–250 g. were housed in a constant temperature environment with free access to food and