Search

We investigate the nature of the ULX M81 X-6, which has been suggested to harbour a neutron star (NS), by studying its long-term X-ray spectral and temporal evolution, using the rich set of available archival data from XMM-Newton, Chandra, NuSTAR, and Swift/XRT. We tracked the evolution of the source on the hardness-intensity diagram and find that the source oscillates between two main states: one characterised by a hard and luminous spectrum and the other at low hardness and luminosity. The properties of the soft component remain constant between the two states, suggesting that changes in the mass-transfer rate are not driving the spectral transitions. Instead, the bi-modal behaviour of the source and the known super-orbital period would point to the precession of the accretion disc. Here, we tested two theoretical models: (1) Lense-Thirring precession, which can explain the super-orbital period if the NS has a magnetic field $B$ $\lesssim10^{10}$ G, supporting the idea of M81 X-6 as a weakly magnetised NS, and (2) precession due to the torque of the NS magnetic field, which leads to $B \gtrsim$ 10$^{11}$ G. However, the latter scenario, assuming M81 X-6 shares similar properties with other NS-ULXs, is disfavoured because it would require magnetic field strengths ($B>10^{15}$ G) much higher than those known for other pulsating ULXs. We further show that the contribution from the hard component attributed to the putative accretion column sits just below the typical values found in pulsating ULXs, which, together with the low value of the pulsed fraction ($\leq10$\%) found for one XMM-Newton/pn observation, could explain the source's lack of pulsations. The spectral properties and variability of M81 X-6 can be accounted for if the accretor is a NS with a low magnetic field. Under the hypothesis of Lense-Thirring precession, we predict a spin period of the NS of a few seconds., 14 pages, 10 figures. Accepted for publication on Astronomy & Astrophysics

Relativistic Fe K emission lines from accretion disks and from disk winds encode key information about black holes, and their accretion and feedback mechanisms. We show that these two processes can in principle produce indistinguishable line profiles, such that they cannot be disentangled spectrally. We argue that it is likely that in many cases both processes contribute to the net line profile, and their relative contributions cannot be constrained purely by Fe K spectroscopy. In almost all studies of Fe K emission to date, a single process (either disk reflection or wind Compton scattering) is assumed to dominate the total line profile. We demonstrate that fitting a single process emission model (pure reflection or pure wind) to a hybrid line profile results in large systematic biases in the estimates of key parameters, such as mass outflow rate and spin. We discuss various strategies to mitigate this effect, such as including high energy data covering the Compton hump, and the implications for future X-ray missions., Comment: 22 pages, 17 figures, accepted for publication in MNRAS

Background Physiotherapists for adults with intellectual disabilities often work in day centres, relying on care staff to support programmes. This study investigates factors affecting physiotherapy delivery in 4 day centres in one London borough. Materials and Method Semi-structured interviews were carried out with day centre care staff, managers and physiotherapists. Results Service users’ needs were reported not to be met at three of the four centres. Barriers included low staffing levels, high absences and use of agency staff. Relevant variables included level of physiotherapist attendance, management priorities for care staff time, care staff confidence and whether a consistent team support delivery. Discrepancies emerged between staff and physiotherapists’ views on training needs. Conclusions Physiotherapy delivered in day centres is an important part of a complex care package. It requires effective multiagency working to meet the known – and potentially unidentified – needs of individuals and to ensure that care staff are adequately supported.

A high resolution fast readout camera system has been dCVCIOPeJdarOWKI a specialised full frame 512 512 pixel format CCD sensor in conjunction with EEV Ltd. An eqwvalentreadoutrate of 600 frames per second with a spatial resolution of24 line pairs pet mm at the Nyquist limit is achieved. A binning capability increases the readout rate by up to a ftorof four. The system dynamic range is in excess of 1000 : 1.System features include image analysis by computer with dedicatedsoftware, non volatile memory ,highresolution andrealtime displays, instantly reset able, single shot image capture capability and remote head operation. 2 . INTRODUCTIONConvential CCD architectore has not been able to hieve fast readout with attendant high spatial resolution and highdynamic range.Thereare variants of hieving fast rea&rnt using solid state image technology with constraints on both of these parameters such as the Fairchild 222 1 CCD and Reticon photo diode arrays.Foilowing an in house technical wogram

Agricultural and urban development of the coastal floodplains of New South Wales has involved major changes in the extent of natural habitats and in the decline of the state’s coastal wetlands – the programme of structural flood mitigation works in all major river systems. The stated aims of these works are to reduce the frequency of flooding in low-lying control areas, to facilitate removal of floodwaters after floods and to control flooding which cannot be prevented (NSW Department of Public Works, 1973). In practice, the pursuit of these aims has led to the elimination of reduction in value of much freshwater and estuarine wetland. While the benefits of flood mitigation to agricultural and urban economics have been significant and well documented (eg/ Macleay River County Council et al., 1963; Executive Committee for Councils, 1968) assessment of the adverse effects, particularly environmental impacts, has been limited (McGregor, 1979; Middleton et al., in press). Of the recent studies which have considered environmental aspects of specific proposals, few have included a systematic analysis of major potential impacts. Fewer still have generated new background information on the areas concerned and the authors know of no study which has considered all flora and fauna potentially affected. Notably, this general lack of environmental research applies to the recent series of floodplain management studies on major river systems in coastal New South Wales, few of which analysed the specific impacts of existing or proposed works.

In many estuaries of New South Wales (N.S.W.), agricultural, urban, and industrial activities have benefited at the expense of naturally occurring attributes such as commercial and amateur fisheries, wildlife habitats, recreational resources, and esthetic and cultural values. The successful future management of the estuarine environment is contingent on a number of factors, including a paucity of baseline data, a lack of predictive models, the difficulty of quantifying natural attributes, and a previous tendency to study the effects of each development proposal on an individual rather than on a cumulative basis. A positive step in estuarine management was recently taken by the N.S.W. government with the passage of legislation whereby environmental considerations are incorporated into planning and management procedures. However, shortcomings still exist in the overall management approach. This paper illustrates some of these shortcomings by examining the adverse environmental effects of structural...

Since 1971 over 100 specimens of the oriental goby, Acanthogobius flavimanus, have been collected from New South Wales’ waters. When this species, a native of Japan, was introduced to San Francisco Bay (U.S.A.) it underwent a population explosion, becoming a common member of estuarine fish communities in that area. The occurrence of both reproductively maturing females and juveniles in the harbours of the Sydney region (central New South Wales coast) suggests that the species may have bred successfully here. However, the relatively low numbers of A. flavimanus collected during the study indicate that as yet there has been no population explosion in New South Wales waters. A number of aspects of the biology and ecology of the species was examined in an attempt to identify features which may limit its distribution and abundance in the Sydney region. The inhibition of successful reproduction by the relatively warm-water temperatures in this area and the potential for competition with native fishes are proposed as possible explanations.

The structure of fish communities inhabiting separate meadows of the seagrasses Zostera capricorni Aschers. and Posidonia australis Hook f. in Botany Bay, central New South Wales, was studied over a 2-year period using a number of community parameters. The heterogeneity, species richness and total abundance of fishes were not found to be significantly different between the two seagrass habitats, although more species and more individuals were associated with Zostera. The number of species, abundance of individuals and total biomass were all significantly greater in both habitats during summer, and total biomass was significantly greater in the Posidonia. Ordination of species abundance data separated samples from the two habitats. In general, larger species of the Gobiidae and Syngnathidae were diagnostic of Posidonia and smaller members of these families were unique to, or more abundant in, Zostera. Occurrence, abundance and biomass data were used to identify the 20 dominant members of the fish community in each habitat. About 50% of the dominant fish species associated with each seagrass habitat were of some economic importance. Such species were usually residents or transients and made up most of the biomass in each habitat. Adults of these dominant economically important species were most abundant in both seagrass habitats during summer. Juveniles of several economically important species were present in both Posidonia and Zostera meadows. However, marked differences in time of occurrence, size and feeding behaviour of these juveniles between the two habitats suggest that such species use Zostera and Posidonia meadows sequentially. Differences in the structure of the communities, and utilization of resources by juveniles of several economically important species, appear to be related to variations in the structural complexity of the canopies created by the two seagrasses.

Summary1) The basal level of endogenously supplied nitrogen in adult rats is about 5 mg after 1 1/2 hours, and this level is unaffected by protein depletion. On feeding skim milk powder, 22–27% of the ingested protein disappeared from the gastrointestinal tract within 3 hours. Under the conditions of these experiments the alleged homeostatic action of the gut in supplementing amino acids to deficient protein meals may be only negligible. 2) No significant differences have been observed in gastric emptying time, rate of absorption, or digestion between skim milk powders dried at low or high temperature.

Groups of weanling rats were fed diets containing various levels of galactose or glucose or both. The excretion of amino acids was not affected by the type or quantity of ingested carbohydrate. It seems likely, therefore, that the aminoaciduria observed in galactosemic infants must be due to some cause other than the toxic effects of galactose itself or a competition for the renal reabsorption mechanism.

The fish assemblage in the lower reaches of a temperate tidal mangrove creek entering Botany Bay near Sydney, New South Wales, was sampled using rotenone every second month between December 1977 and October 1980. Almost 17 000 fish (weight ~ 115 kg), belonging to 46 species and 24 families, were collected. Six species dominated the assemblage and another four were relatively common. Fourteen species, including four of the above, were economically important. These fishes made up 38% of individuals and 32% of biomass and were represented only by small juveniles. Nineteen species (41%) were temporary residents; these mainly comprised juveniles of large species that live elsewhere as adults. Fifteen species (33%), most of which only attain a small size (< 100 mm), were assumed to be permanent residents. The remaining 12 species (26%) occurred in only one sample and were, therefore, classified as rare. The diversity (HI) and evenness (J') of the fish community were low and showed little seasonality because a few species dominated the assemblage on an irregular basis. Numbers of species and of individuals varied seasonally and were significantly correlated. Peaks in these parameters lagged behind those in water temperature by 4 months and were largely the result of the relatively restricted recruitment periods of several abundant temporary resident species. The large numbers of juveniles and small species in the mangrove creek habitat were attributed to the availability of suitable shelter and food for such small fishes. Concerted use of the mangrove habitat by several abundant temporary resident species during the same general period each year appeared to be facilitated by the occupation of otherwise vacant feeding niches and some staggering of their peak recruitment periods. Exclusive use of this habitat by small juveniles of several species in Botany Bay confirms that mangrove habitats in temperate Australia, like some of those studied in tropical and subtropical regions, are important nursery areas for fishes inhabiting adjacent estuarine and inshore marine habitats as adults.