It has long been recognised that the Neolithic spread across Europe via two separate routes, one along the Mediterranean coasts, the other following the axis of the major rivers. But did these two streams have a common point of origin in south-west Asia, at least with regard to the principal plant and animals species that were involved? This study of barley DNA shows that the domesticated barley grown in Neolithic Europe falls into three separate types (groups A, B and C), each of which may have had a separate centre of origin in south-west Asia. Barley was relatively rarely cultivated by the early Linearbandkeramik farmers of Central and Northern Europe, but became more common during the fifth and fourth millennia BC. The analysis reported here indicates that a genetic variety of barley more suitable for northern growing conditions was introduced from south-west Asia at this period. It also suggests that the barley grown in south-eastern Europe at the very beginning of the Neolithic may have arrived there by different routes from two separate centres of domestication in south-west Asia. The multiple domestications that this pattern reveals imply that domestication may have been more a co-evolutionary process between plants and people than an intentional human action.

Polarimetry at far-infrared wavelengths is a key tool for studying physical processes on size scales ranging from interstellar dust grains to entire galaxies. A multi-wavelength continuum polarimeter at these wavelengths will allow studies of thermal dust polarization in an effort to constrain the grains’ physical properties and test grain alignment theory. High spatial resolution (5–30 arcsec) and sensitive observations will measure the influence of magnetic fields on infrared cirrus clouds, the envelopes and disks of YSOs, outflows from both low- and high-mass star forming regions, and the relative strength of magnetic, gravitational, and turbulent effects in star- and cloud-formation.

The pond turtle (Trachemys scripta elegans) exhibits a notably sluggish pupillary light reflex (PLR), with pupil constriction developing over several minutes following light onset. In the present study, we examined the dynamics of the efferent branch of the reflex in vitro using preparations consisting of either the isolated head or the enucleated eye. Stimulation of the oculomotor nerve (nIII) using 100-Hz current trains resulted in a maximal pupil constriction of 17.4% compared to 27.1% observed in the intact animal in response to light. When current amplitude was systematically increased from 1 to 400 μA, mean response latency decreased from 64 to 45 ms, but this change was not statistically significant. Hill equations fitted to these responses indicated a current threshold of 3.8 μA. Stimulation using single pulses evoked a smaller constriction (3.8%) with response latencies and threshold similar to that obtained using train stimulation. The response evoked by postganglionic stimulation of the ciliary nerve using 100-Hz trains was largely indistinguishable from that of train stimulation of nIII. However, application of single-pulse stimulation postganglionically resulted in smaller pupil constriction at all current levels relative to that of nIII stimulation, suggesting that there is amplification of efferent drive at the ganglion. Time constants for constrictions ranged from 88 to 154 ms with relaxations occurring more slowly at 174–361 ms. These values for timing from in vitro are much faster than the time constant 1.66 min obtained for the light response in the intact animal. The rapid dynamics of pupil constriction observed here suggest that the slow PLR of the turtle observed in vivo is not due to limitations of the efferent pathway. Rather, the sluggish response probably results from photoreceptive mechanisms or central processing.

X rays emitted from Kr clusters illuminated by a femtosecond laser have been observed over a wide spectral region from 3 keV to 15 keV. The measured spectra are characterized by a broad bremsstrahlung continuum and Kα, β lines at 12.66 keV and 14.1 keV. To the best of the authors' knowledge, this is the first observation of Kα, β emission from laser-heated Kr clusters. The bremsstrahlung continuum arising from collisions in the plasma implies a population of hot electrons consistent with a temperature of several kiloelectron volts. The absolute X-ray yield in the 3–15 keV region is found to be of the order of 107 photons per laser pulse. The plasma temperature, estimated from the continuum part of the spectrum as a function of laser intensity and X-ray yield as a function of laser pulse duration, are studied.

Lake sediments in the Larsemann Hills contain a great diversity of biological and physical markers from which past environments can be inferred. In order to determine the timing of environmental changes it is essential to have accurate dating of sediments. We used radiometric (210Pb and 137Cs), radiocarbon (AMS 14C) and uranium series (238U) methods to date cores from eleven lakes. These were sampled on coastal to inland transects across the two main peninsulas, Broknes and Stornes, together with a single sample from the Bolingen Islands. Radiometric dating of recent sediments yielded 210Pb levels below acceptable detection limits. However, a relatively well-defined peak in 137Cs gave a date marker which corresponds to the fallout maximum from the atmospheric testing of atomic weapons in 1964/65. Radiocarbon (AMS 14C) measurements showed stratigraphical consistency in the age-depth sequences and undisturbed laminae in some cores provides evidence that the sediments have remained undisturbed by glacial action. In addition, freshwater surface sediments were found to be in near-equilibrium with modern 14CO2 and not influenced by radiocarbon contamination processes. This dating program, together with geomorphological records of ice flow directions and glacial sediments, indicates that parts of Broknes were ice-free throughout the Last Glacial Maximum and that some lakes have existed continuously since at least 44 ka bp. Attempts to date sediments older than 44 ka bp using 128U dating were inconclusive. However, supporting evidence for Broknes being ice-free is provided by an Optically Stimulated Luminescence date from a glaciofluvial deposit. In contrast, Stornes only became ice-free in the mid to late Holocene. This contrasting glacial history results from the Dålk Glacier which diverts ice around Broknes. Lakes on Broknes and some offshore islands therefore contain the oldest known lacustrine sediment records from eastern Antarctica, with the area providing an ice-free oasis and refuge for plants and animals throughout the Last Glacial Maximum. These sediments are therefore well placed to unravel a unique limnological sequence of environmental and climate changes in East Antarctica from the late Pleistocene to the present. This information may help better constrain models of current climate changes and ensure the adequate protection of these lakes and their catchments from the impacts of recent human occupation.

We describe preliminary results from our study of multi-scale structures in Centaurus A (NGC 5128) obtained using the Chandra X-ray Observatory HRC-I observations. The high-angular resolution Chandra images reveal X-ray multi-scale structures in this object with unprecedented detail and clarity. The region surrounding the Cen A nucleus, believed to be associated with a supermassive black hole, shows structures on arcsecond scales clearly resolved from the central source.

In previous research the benefits of grass feeding in lambs for healthiness (fatty acid composition) and flavour have been demonstrated (Fisher et al., 2000). This work examined a very short period of feeding grass or concentrates in a hill breed (Beulah) and a breed noted for meat production (Texel).

Red wheats (Triticum aestivum L.) are generally more dormant and sprout resistant than white wheats. Whether this is caused by pleiotropic effectsof the red grain colour genes (R) on dormancy and coat colour, or to tight linkage between R and dormancy genes has not been fully resolved. To directly determine the effect of the R1 allele on dormancy, mutations were induced with sodium azide in a pure line selection of the red genotype (R1R1r2r2r3r3) Chinese Spring wheat. Two white mutants (CSW01, CSW02) were recovered from M3 caryopses derived from approximately 20,000 M2 plants. Both mutants were shown to be allelic to a domesticwhite genotype (r1r1r2r2r3r3). Except for seed coat colour, CSW01 and CSW02 are morphologically indistinguishable from the wild type and are presumed to be near isogenic lines of Chinese Spring. Freshly harvested grainsproduced under four different environments were evaluated for post-harvest dormancy. In all environments, intact caryopses of all three isolines exhibited high temperature dormancy typical of cereal species, although the red wild type consistently exhibited greater dormancy than the white mutant isolines. Dormancy was dissipated by afterripening in dry storage at 37°C in a similar manner for the red and white isolines. Excised embryos of the three isolines exhibited similar levels of dormancy and sensitivities to exogenous abscisic acid. These results indicate a functional R1 allele is not absolutely required for dormancy in wheat, but does enhance its expression in caryopses with dormant (sensitive) embryos

Quantitative sampling for the genus Eurydice (Isopoda: Cirolanidae) was conducted on 25 sand beach sites along the Atlantic coast of the Iberian Peninsula. Five species were recorded intertidally: Eurydice affinis, E. pulchra, E. naylori sp. nov., E. lusitaniensis sp. nov. and E. spinigera. Physical data collected were used to construct an index of exposure to rank each site. The distribution of intertidal Eurydice sp. is described in relation to exposure to wave action and to tidal level. Peak abundance of E. affinis, E. pulchra and naylori occurred most frequently between mean high water neap (MHWN) and mean tide level (MTL). Whilst E. affinis occurred over a wide range of exposure, E. naylori exhibited a marked preference for exposed sites and E. pulchra was only recorded from sheltered and semi-exposed sites. Surf plankton collections revealed the presence of E. lusitaniensis, but as only two specimens were collected, its ecology remains unknown. The zoogeographical distribution of the genus on North Atlantic and Mediterranean coasts is briefly reviewed.

Trypsin-like enzyme activity of the larvae of two planktonic predatory crustaceans, Homarus gammarus and Nephrops norvegicus (Decapoda: Nephropidae) and the omnivorous larvae of Carcinus maenas (Decapoda: Brachyura) were investigated at each larval stage until metamorphosis. Two copepods, herbivorous or omnivorous grazers, Centropages typicus and Temora longicornis (Copepoda: Calanoidae) were also investigated for this enzyme. A comparison of trypsin-like activity in these and other decapod larvae shows a pattern with high levels in herbivores, low levels in carnivores and intermediate levels in omnivores. Herbivorous planktonic crustaceans appear to rely on high digestive enzyme activities to extract nutrients from less digestible algae or particulates, whereas carnivorous larvae have limited enzymatic capacity as they feed at higher trophic levels upon large and easily digestible prey. Omnivorous Carcinus maenas larvae have intermediate levels of digestive enzymes and are able to transfer between herbivorous and omnivorous feeding.

Conformation is often given high priority as a selection objective by pedigree breeders who consider this trait to be related to lean yield and distribution, despite experimental evidence to the contrary. The Texel crossbred lamb is known to have a high lean yield at a given liveweight and in considering the results of breed comparison trials Croston et al (1987) speculated that there may be variation between strains for this trait, possibly associated with differences in conformation. Support for this suggestion comes from the work of Leroy (1989) who reported that the Belgian Texel with a heavily muscled conformation (“double muscled”) had a higher killing-out proportion and lean yield than sheep with conventional shape. The aim of this trial was to investigate potential differences in the carcass traits of pure-bred Texel lambs of extreme versus conventional conformation

The Wide-Field and Planetary Camera (WF/PC) is a CCD imaging instrument which is part of the Hubble Space Telescope. Ground-based observations have been made with a CCD system similar to those of the WF/PC in order to establish the standard star sequence to be used for in-flight photometric calibration. Because the WF/PC passbands differ from those in previous photometric use, the filters and CCDs will define a new photometric system. We outline here the procedures used to establish the calibration fields to be used in flight (see Harris et al. 1988 for additional details).

Sward growth rate and height decline under autumn grazing in the UK. This eventually depresses ewe intake, live weight and body condition and may, as a consequence, reduce reproductive performance. The provision of supplementary feeding is a strategic measure to avoid this but requires quantification in relation to measurable variables such as sward height and stage of the reproductive cycle.

A management decision rule for supplementary feeding over the mating period, which is currently operated in the MLURI upland system studies, requires that, in order to maintain both body weight and condition until the completion of the second cycle of mating, concentrated feed be introduced when sward height (herbage mass) is ≤3.5 cm (≤1200 kg DM/ha), be increased when height is ≤3.0 cm ( ≤ 1000 kg DM/ha) and ad lib, hay be introduced when height is ≤ 2.5 cm (≤ 750 kg DM/ha).