Schizophrenia is associated with altered neural development. We assessed neurological soft signs (NSS) and dermatoglyphic anomalies (total a–b ridge count (TABRC) and total finger ridge count) in 15 pairs of twins concordant and discordant for schizophrenia. Within-pair differences in both NSS and TABRC scores were significantly greater in discordant compared to concordant monozygotic pairs. There was no significant difference in NSS and TABRC scores between subjects with schizophrenia and their co-twins without the illness. However, monozygotic discordant twins with schizophrenia had higher ABRCs on their right hands compared to their co-twins without the illness. These findings suggest that an unidentified environmental event acting between weeks 6 and 15 of gestation affects the development of monozygotic twins who go on to develop schizophrenia but does not have a corresponding effect on their co-twins who do not develop the illness. The effect of such an event on dermatoglyphic profiles appears lateralised to the right hand in affected twins.

Although there is some evidence that duration of untreated psychosis (DUP) is geographically stable, few have examined whether the phenomenon is temporally stable. We examined DUP in two cohorts within two discrete time periods (1995–1999 and 2003–2005) spanning a decade in the same geographically defined community psychiatric service with no early intervention programme. Patients were diagnosed by Structured Clinical Interview for DSM (SCID) and we determined the DUP using the Beiser Scale. The DUP of the 240 participants did not differ significantly between study periods.

As research into psychotic illness evolves along established lines, insights are emerging that deviate from those lines and challenge more fundamentally our understanding. On the background of a new generation of studies on first-episode psychosis, investigations across the gene–environment interface and the intersection with ‘normal’ human mentation heighten these concerns. Using findings from the Cavan-Monaghan First Episode Psychosis Study (CAMFEPS) as an exemplar, we here review the complexity of these challenges from the perspective of this real-world setting. They range from trans-diagnostic epidemiology and clinical characterisation, through molecular genetics, social milieu, developmental pathobiology and functional outcome across arbitrary diagnostic boundaries, to the evidence base for early intervention and more radical conceptualisations and structures for provision of mental health care.

As part of a project to investigate the flow of ice at low effective stress, two independent strain-gauge systems were used to measure vertical strain rate as a function of depth and time at Siple Dome, Antarctica. The measurements were made from January 1998 until January 2002 at the ice divide and a site 7km to the northeast on the flank. The strain-rate profiles place constraints on the rheology of ice at low stress, show the expected differences between divide and flank flow (with some structure due to firn compaction and probably ice stratigraphy), and suggest that the flow of the ice sheet has not changed much in the last 8.6 kyr. The strain rates show an unexpected time dependence on scales ranging from several months to hours, including discrete summer events at the divide. Time dependence in strain rate, water pressure, seismicity, velocity and possibly basal motion has been seen previously on the Siple Coast ice streams, but it is especially surprising on Siple Dome because the bed is cold.

We used observations and modeling of Siple Dome, West Antarctica, a ridge ice divide, to infer the importance of linear deformation mechanisms in ice-sheet flow. We determined the crossover stress (a threshold value of the effective deviatoric stress below which linear flow mechanisms dominate over nonlinear flow mechanisms) by combining measurements of ice properties with in situ deformation rate measurements and a finite-element ice flow model that accounts for the effects of viscous anisotropy induced by preferred crystal-orientation fabric. We found that a crossover stress of 0.18 bar produces the best match between predicted and observed deformation rates. For Siple Dome, this means that including a linear term in the flow law is necessary, but generally the flow is still dominated by the nonlinear (Glen; n = 3) term. The pattern of flow near the divide at Siple Dome is also strongly affected by crystal fabric. Measurements of sonic velocity, which is a proxy for vertically oriented crystal fabric, suggest that a bed-parallel shear band exists several hundred meters above the bed within the Ice Age ice.

Lack of agreement between the deep portions of the Greenland Icecore Project (GRIP) and Greenland Ice Sheet Project II (GISP2) ice cores from central Greenland suggests that folds may disrupt annual layering, even near ice divides. We use a simple kinematic flow model to delineate regions where slope disturbances (“wrinkles”) introduced into the layering could overturn into recumbent folds, and where they would flatten, leaving the stratigraphic record intact. Wrinkles are likely to originate from flow disturbances caused internally by inhomogeneities and anisotropy in the ice rheological properties, rather than from residual surface structures (sastrugi), or from open folds associated with transient flow over bed topography. If wrinkles are preferentially created in anisotropic ice under divides, where the resolved shear stress in the easy-glide direction can be weak and variable, then the deep intact climate record at Dye 3 may result from its greater distance from the divide. Alternatively, the larger simple shear at Dye 3 may rapidly overturn wrinkles, so that they are not recognizable as folds. The ice-core record from Siple Dome may be intact over a greater fraction of its depth compared to the central Greenland records if its flat bedrock precludes fluctuations in the stress orientation near the divide.

As part of a larger program to measure and model vertical strain around Siple Dome on the West Antarctic ice sheet, we developed a new sensor to accurately and stably record displacements. The sensors consist of optical fibers, encased in thin-wall stainless-steel tubes, frozen into holes drilled with hot water, and stretched from the surface to various depths (up to 985 m) in the ice sheet. An optical system, connected annually to the fibers, reads out their absolute lengths with a precision of about 2 mm. Two sets of five sensors were installed in the 1997/98 field season: one set is near the Siple Dome core hole (an ice divide), and a second set is on the flank 7 km to the north (the ice thickness at both sites is approximately 1000 m). The optical-fiber length observations taken in four field seasons spanning a 3 year interval reveal vertical strain rates ranging from −229 ± 4 ppm a−1 to −7 ± 9 ppm a−1. In addition to confirming a non-linear constitutive relationship for deep ice, our analysis of the strain rates indicates the ice sheet is thinning at the flank and is in steady state at the divide.

Seedling alfalfa was injured by chlorsulfuron and sethoxydim plus 2,4-DB but recovered the following year as alfalfa seed yields were comparable to the hand-weeded control. Fluazifopbutyl and flamprop-methyl (active isomer) at 0.5 kg/ha did not affect seedling alfalfa adversely; however, seed yields were lower the following year compared to those treated at the 0.25-kg/ha rate. In established alfalfa, sethoxydim alone or with 2,4-DB applied annually did not affect seed yields adversely. However, 2,4-DB alone reduced seed yields in 2 of 5 yr. Alfalfa tolerated chlorsulfuron at 0.015 kg/ha but was damaged at the 0.03-kg/ha rate. Initial injury and later recovery without adverse effects on seed yield also were observed following annual treatments with bromoxynil, MCPA plus 2,4-DB and bentazon plus 2,4-DB.

The long-term effect of repeated late-fall versus early-spring imazethapyr, hexazinone, terbacil, metribuzin, dichlobenil, or chlorsulfuron treatments, when applied on dormant stands of alfalfa was investigated at three sites for weed management of alfalfa grown for seed. Dichlobenil applied at 1.2 to 2.4 kg ha−1 and chlorsulfuron applied at 11 to 22 g ha−1 in fall or spring were the only herbicides to injure alfalfa at one location. Hexazinone provided the most consistent weed control of the herbicides evaluated. Average control of Canada thistle, catchweed bedstraw, dandelion, perennial sowthistle, quackgrass, Russian pigweed, and scentless chamomile was 80%. When averaged over three sites, weed control by hexazinone resulted in a 33% increase in seed yield.

Tolerance and subsequent yield response of established alfalfa, red clover, alsike clover, sainfoin, birdsfoot trefoil, and cicer milkvetch to sethoxydim and fluazifop spring applied and to hexazinone, metribuzin, and terbacil fall applied were determined in a field study. All legumes tolerated sethoxydim. Fluazifop was safe on all legumes except sainfoin. Alfalfa and cicer milkvetch tolerated hexazinone, metribuzin, and terbacil. Alfalfa dry matter yield was not affected by any of the herbicide treatments, but cumulative cicer milkvetch yield increased 9% over a 3-yr period with hexazinone applications. Sainfoin yield increased 20% with hexazinone and terbacil treatment. Hexazinone injured red clover and reduced yield. Alsike clover was the most susceptible legume to the residual herbicides. Weed dry matter yield associated with the legumes indicated that alfalfa and sainfoin were the most and the least competitive species, respectively. Plots treated with hexazinone contained the least amount of weeds, regardless of the legume species. Field peas seeded in rotation was not affected by herbicide residues; however, residues from terbacil applied at 1.0 kg/ha reduced seed yield of lentils.

Applications of 1.6 kg ai/ha of metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] to established alfalfa (Medicago sativa L. ‘Rambler’) at the start of each growing season for 4 yr increased seed yield by 68% and controlled established dandelion (Taraxacum officinale Weber. in Wiggers ♯ TAROF) and smooth brome (Bromus inermis Leyss. ♯ BROIN). A lesser amount of metribuzin was not sufficient for smooth brome control, and a greater amount damaged the alfalfa. Hexazinone [3-cyclohexyl-6-(dimethylamino)-methyl-1,3,5-triazine-2,4(1H,3H)-dione] applied at 1.0 kg ai/ha also controlled dandelion and smooth brome and produced increases in alfalfa seed yield. Mixtures of terbacil (3-tert-butyl-5-chloro-6-methyluracil) with reduced rates of metribuzin or hexazinone controlled dandelion well, but gave only fair control of smooth brome. Alfalfa seed yield was negatively correlated with the smooth brome population.

The recovery of past climatic conditions from ice-sheet borehole temperatures can best be accomplished using the calculus of variations (control methods) to minimize mismatch between the observed profile and a solution of the heat equation which depends on the unknown climate history. Here, we use control methods and a simple one-dimensional heat equation and the temperature depth profile observed at Dye-3 to infer the surface temperature of south Greenland over the last 30 000 years. This history illustrates the virtues that recommend control methods for future use in borehole-temperature analysis, namely: (i) it meets objective performance criteria, and (ii) its uncertainty can be established quantitatively. Our inferred climate history displays what may be the Younger Dryas cold event at about 9000 years BP. Borehole paleothermometry by control methods may thus resolve the controversy concerning the interpretation of Greenland ice-core isotope records.

The climatic record from Greenland boreholes is likely to extend well beyond the last interglacial only if the basal ice near the drilling sites has never reached its pressure melting point (−2°C). A simplified one-dimensional analysis (Paterson and Waddington, 1986) suggested that this would be true at Crête, Greenland, if the geothermal flux was less than 48 mW m−2. In that study, the vertical velocity pattern for an isothermal ice sheet was used. We have repeated the Crête calculations using the vertical velocity pattern derived by a finite element analysis. Using this temperature-dependent velocity pattern lowered the basal temperature by about 3°C.

We have carried out a similar analysis for the Summit coring site further north on the Greenland ice divide. Here we find that the basal ice does not melt if the geothermal flux is less than 54 mW m−2, using the same mass balance and surface temperature histories as the previous study. We are repeating these one-dimensional calculations with more recently compiled histories and plan to present results from a full two-dimensional temperature model that includes processes only parameterized in the one-dimensional models. Using two dimensions, we will more realistically incorporate the special ice-flow patterns found at divides (e.g. Raymond, 1983; Dahl-Jensen, 1989). In steady-state flow models these patterns lead to significant horizontal temperature gradients and a “hot spot” beneath an ice divide (Paterson and Waddington, 1986). In addition, we will more accurately determine the transient effects on basal temperature resulting from the interaction of these flow patterns and the changing climate. Our discussion will include sensitivity to geothermal heat flux, ice thickness and paleoenvironmental history.

The deep-drilling projects at the Summit ice divide will require thermal models to help interpret the paleoclimatic signals in their cores. An analytic, steady-state model predicts basal temperatures within 1 °C of the ice melting-point and basal ice no older than 100–400 kyear should melting occur. A two-dimensional, time-dependent temperature model includes the effects of realistic two-dimensional ice flow and the temperature and mass-balance patterns of the last two glacial cycles. The model relaxes some assumptions made in one-dimensional studies and produces lower basal temperatures. The basal temperatures are most sensitive to the value of the geothermal heat flux and the mass-balance pattern. If the flux is less than 56 mW m−2, the bed has likely been frozen throughout the last glacial cycle. The decoupling of the energy and mass-conservation equations is a significant source of error which can be eliminated only by a fully coupled ice-flow/ heat-flow model.