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The article discusses how the prison system in Great Britain was reformed during the reign of Queen Victoria. Topics include reformer John Howard's accounts of the country's prisons as establishments designed to spread ill behavior, shifts in public beliefs regarding prisons, the centralization of the prison system, changes to how the death penalty was carried out, model prisons and transportation of convicts.

The icy Galilean satellites display impact crater morphologies that are rare in the Solar System. They deviate from the archetypal sequence of crater morphologies as a function of size found on rocky bodies and other icy satellites: they exhibit central pits in place of peaks, followed by central dome craters, anomalous dome craters, penepalimpsests, palimpsests, and multi‐ring structures. Understanding the origin of these features will provide insight into the geophysical factors that operate within the icy Galilean satellites. Pit craters above a size threshold feature domes. This trend, and the similarity in morphology between the two classes, suggest a genetic link between pit and dome craters. We propose that dome craters evolve from pit craters through topographic relaxation, facilitated by remnant heat from the impact. Our finite element simulations show that, for the specific crater sizes where we see domes on Ganymede and Callisto, domes form from pit craters within 10 Myr. Topographic relaxation eliminates the stresses induced by crater topography and restores a flat surface: ice flows downwards from the rim and upwards from the crater depression driven by gravity. When the starting topography is a pit crater, the heat left over from the impact is concentrated below the pit. Since warm ice flows more rapidly, the upward flow is enhanced beneath the pit, leading to the emergence of a dome. Given the timescales and the dependence on heat flux, this model could be used to constrain the thermal history and evolution of these moons. Ganymede and Callisto are large icy moons orbiting Jupiter, believed to be ocean worlds. These moons' surfaces display impact craters with shapes not seen elsewhere in the Solar System. This may be due to factors such as their high gravity, temperature, presence of subsurface oceans, and/or impactor characteristics. By exploring these atypical craters, we aim to shed light on the inner workings and evolution of these moons and, by extension, contribute to a clearer picture of the evolution of the outer Solar System. This study focuses on unveiling the origins of dome craters on Ganymede and Callisto, which have rounded bright domes in the center and are virtually unique to these moons. We believe these domes are connected to a relatively more common crater, the pit crater. Our simulations show that a pit crater can evolve into a dome crater within 10 million years as the ice flows slowly under its own weight. This flow is channeled back into the center creating a dome, aided by warm temperatures left over from the impact that soften the ice below the pit. This occurs only for the specific sizes where we see dome craters on these moons. Dome craters form via topographic relaxation of pit craters for sizes larger than ∼60 kmRemnant heat from the impact enhances relaxation at the center of the pit crater, causing domes to emergeEven young dome craters can form from the relaxation of pit craters due to the relatively short timescales required (∼10 million years) Dome craters form via topographic relaxation of pit craters for sizes larger than ∼60 km Remnant heat from the impact enhances relaxation at the center of the pit crater, causing domes to emerge Even young dome craters can form from the relaxation of pit craters due to the relatively short timescales required (∼10 million years)

ABSTRACTOn the 27 April 1853, in the Birmingham borough prison, a fifteen-year-old prisoner, Edward Andrews, killed himself. His death led to a Royal Commission which explored the operation of the prison since its opening in 1849. Over thirteen days magistrates, the prison’s officers, guards and former and serving prisoners gave evidence in public. The commission’s 531-page report provided a remarkable and unique insight into life in the prison. This paper provides a detailed account of events in Birmingham and the political context that enabled such a thorough investigation. It highlights the contributions of the radical Birmingham Councillor, Joseph Allday, and Home Secretary, Viscount Palmerston, to explain why an investigation took place. Whilst previous accounts have blamed the abuses on the regime of ‘terror’ of the prison’s second governor, William Austin, this article argues that their origins can be traced back to the reformative regime of the first governor, Alexander Maconochie.

Rosetta observations of 67P/Churyumov‐Gerasimenko (67P) reveal that most changes occur in the fallback‐generated smooth terrains, vast deposits of granular material blanketing the comet's northern hemisphere. These changes express themselves both morphologically and spectrally across the nucleus, yet we lack a model that describes their formation and evolution. Here we present a self‐consistent model that thoroughly explains the activity and mass loss from Hapi's smooth terrains. Our model predicts the removal of dust via reradiated solar insolation localized within depression scarps that are substantially more ice rich than previously expected. We couple our model with numerous Rosetta observations to thoroughly capture the seasonal erosion of Hapi's smooth terrains, where local scarp retreat gradually removes the uppermost dusty mantle. As sublimation‐regolith interactions occur on rocky planets, comets, icy moons, and Kuiper belt objects, our coupled model and observations provide a foundation for future understanding of the myriad of sublimation‐carved worlds. We report the discovery of transient, migrating depressions within the smooth terrains on comet 67PMigration is via uniform scarp retreat, which removes regolith completely from the nucleus and is driven by sublimating subsurface water iceWe develop a model that fully captures our own, and many previous, disparate observations, with implications for how comets seasonally erode

The unusual dark red coloration of Charon’s northern polar cap is shown to be produced from hydrocarbons that are cold-trapped from Pluto’s escaping atmosphere during winter.

The vast, deep, volatile-ice-filled basin informally named Sputnik Planum is central to Pluto’s vigorous geological activity. Composed of molecular nitrogen, methane, and carbon monoxide ices, but dominated by nitrogen ice, this layer is organized into cells or polygons, typically about 10 to 40 kilometres across, that resemble the surface manifestation of solid-state convection. Here we report, on the basis of available rheological measurements, that solid layers of nitrogen ice with a thickness in excess of about one kilometre should undergo convection for estimated present-day heat-flow conditions on Pluto. More importantly, we show numerically that convective overturn in a several-kilometre-thick layer of solid nitrogen can explain the great lateral width of the cells. The temperature dependence of nitrogen-ice viscosity implies that the ice layer convects in the so-called sluggish lid regime, a unique convective mode not previously definitively observed in the Solar System. Average surface horizontal velocities of a few centimetres a year imply surface transport or renewal times of about 500,000 years, well under the ten-million-year upper-limit crater retention age for Sputnik Planum. Similar convective surface renewal may also occur on other dwarf planets in the Kuiper belt, which may help to explain the high albedos shown by some of these bodies.

Evidence from Arrokoth and comets strongly suggests a very low density for this and similar small Kuiper belt objects. Plausible compositions imply high porosities, in excess of 70%, and low compaction crush strengths. If so, impact craters on Arrokoth (especially Sky, its largest) formed largely by compaction of pore space and material displacement. This is consistent with geological evidence from New Horizonsimaging. High porosity reduces cratering efficiency in the gravity regime whereas compaction moves it toward crush strength scaling and increased efficiency. Compaction also guarantees that most impactor kinetic energy is taken up as waste heat near the impact point, with momentum transferred to the rest of the body by elastic waves only. Monte Carlo simulations of Sky‐forming conditions indicate that the momentum imparted likely separated Arrokoth's two lobes, but displacement was limited by dissipation at the neck between them. Unusual strength properties are not required to preserve Arrokoth's bilobate configuration. It has become apparent over the last few years that small asteroids and comets are very underdense compared with the materials they are made of. This means that their total porosities are likely quite high, in excess of 70%, both as tiny voids within particles (so‐called microscopic porosity) and spaces between particles (macroscopic porosity). But none are likely as porous as the distant denizens of the Kuiper belt such as Arrokoth (visited by the New Horizonsspacecraft in 2019). This paper concerns impact craters on Arrokoth and similar small bodies, and the rather unusual effects expected. Imagine a fluffy (fine powder) snowball striking a much larger fluffy snowball, only that the snow is not pure ice but a mixture of porous icy, rocky, and carbon‐rich particles. Even at high velocities (>100 s of m/s) craters should mostly form by compacting pore space and pushing material away from the impact point, not the traditional blasting of ejecta back into space. Similar to crush‐up of an automobile bumper, compaction helps to protect from the potentially catastrophic effects of large impacts, such as complete disruption of the target or breakup of bilobate bodies like Arrokoth, and should be incorporated in future collisional evolution studies. Arrokoth is likely a low density, highly porous, contact binary planetesimalImpact craters on Arrokoth, and particularly its largest, likely formed as compaction craters, with modest or little ejectaHigh porosity acted to protect Arrokoth from catastrophic disruption, ejecta recoil, and lobe dislocation and rearrangement Arrokoth is likely a low density, highly porous, contact binary planetesimal Impact craters on Arrokoth, and particularly its largest, likely formed as compaction craters, with modest or little ejecta High porosity acted to protect Arrokoth from catastrophic disruption, ejecta recoil, and lobe dislocation and rearrangement

To explain the position of the Sputnik Planitia basin on Pluto, the feature would need to have formed via impact and Pluto would need to have a subsurface ocean.

Modelling suggests that the icy region on Pluto known as Sputnik Planitia formed shortly after Charon did and has since been stable, with its latitude corresponding to a minimum in annual solar illumination and its longitude determined by tidal forces from Charon.

Growing agricultural crops in wide row spacings has been widely adopted to conserve water, to control pests and diseases, and to minimise problems associated with sowing into stubble. The development of herbicide resistance combined with the advent of precision agriculture has resulted in a further reason for wide row spacings to be adopted: weed control. Increased row spacing enables two different methods of weed control to be implemented with non-selective chemical and physical control methods utilised in the wide inter-row zone, with or without selective chemicals used on the on-row only. However, continual application of herbicides and tillage on the inter-row zone brings risks of herbicide resistance, species shifts and/or changes in species dominance, crop damage, increased costs, yield losses, and more expensive weed management technology.

AbstractFluorine-rich prismatine, (?,Fe,Mg)(Mg,Al,Fe)5Al4(Si,B,Al)5O21(OH,F), with F/(OH+F) = 0.36–0.40 and hercynite are major constituents of a Fe-Al-B-rich lens in ultrahigh-temperature granulite-facies quartz-sillimanite-hypersthene-cordierite gneisses of the Eastern Ghats belt, Andhra Pradesh, India. Hemo-ilmenite, sapphirine, magnetite, biotite and sillimanite are subordinate. Lithium, Be and B are concentrated in prismatine (140 ppm Li, 170 ppm Be, and 2.8 –3.0 wt.% B2O3). Another Fe-rich lens is dominantly magnetite, which encloses fine-grained zincian ferrohögbomite-2N2S, (Fe2+,Mg,Zn,Al)6(Al,Fe3+,Ti)16O30(OH)2, containing minor Ga2O3(0.30 –0.92 wt.%). Fe-Al-B-rich lenses with prismatine (or kornerupine) constitute a distinctive type of B-enrichment in granulite-facies rocks and have been reported from four other localities worldwide. A scenario involving a tourmalineenriched lateritic precursor affected by dehydration melting is our preferred explanation for the origin of the Fe-Al-B-rich lenses at the five localities. Whole-rock analyses and field relationships at another of these localities, Bok se Puts, Namaqualand, South Africa, are consistent with this scenario. Under granulite-facies conditions, tourmaline would have broken down to give kornerupine-prismatine (±other borosilicates) plus a sodic melt containing H2O and B. Removal of this melt depleted the rock in Na and B, but the formation of ferromagnesian borosilicate phases in the restite prevented total loss of B.

The photoreceptor phytochrome (phy) A has a well-defined role in regulating gene expression in response to specific light signals. Here, we describe a new Arabidopsis mutant, laf1 (long after far-red light 1) that has an elongated hypocotyl specifically under far-red light. Gene expression studies showed that laf1 has reduced responsiveness to continuous far-red light but retains wild-type responses to other light wavelengths. As far-red light is only perceived by phyA, our results suggest that LAF1 is specifically involved in phyA signal transduction. Further analyses revealed that laf1 is affected in a subset of phyA-dependent responses and the phenotype is more severe at low far-red fluence rates. LAF1 encodes a nuclear protein with strong homology with the R2R3-MYB family of DNA-binding proteins. Experiments using yeast cells identified a transactivation domain in the C-terminal portion of the protein. LAF1 is constitutively targeted to the nucleus by signals in its N-terminal portion, and the full-length protein accumulates in distinct nuclear speckles. This accumulation in speckles is abolished by a point mutation in a lysine residue (K258R), which might serve as a modification site by a small ubiquitin-like protein (SUMO).

Abstract:  Studies were conducted to evaluate the relationships among different active N pools of organic matter in soils at two long-term cropping systems in Iowa. Results indicated that multi-cropping systems, particularly meadow-based systems, enhanced bioactivities of soils. Mono-cropping systems, particularly soybean, reduced soil microbial biomass and enzyme activities. The mineralizable N pool (potential N mineralization;N o) was more sensitive to changes in the size of the microbial biomass N (Nmic) than to changes in organic N. One unit change in organic N did not lead to substantial changes in N o, but 1 unit change in Nmic resulted in three or more units change in N o. The active N pools and turnover rate were more sensitive to changes in organic C than to changes in microbial biomass C (Cmic). A unit change in organic C resulted in 10.6 units change in N o, but a unit change in Cmic resulted in only 0.8 unit change in N o. Cmic or Nmic are better indexes than organic C or N for the estimation of N o or N availability, because biomass values are more highly correlated with cumulative N mineralized during 24 weeks of incubation, with r values ranging from 0.57 (P<0.001) to 0.88 (P<0.001).

Abstract:  The impacts of crop rotations and N fertilization on microbial biomass C (Cmic) and N (Nmic) were studied in soils of two long-term field experiments initiated in 1978 at the Northeast Research Center (NERC) and in 1954 at the Clarion-Webster Research Center (CWRC), both in Iowa. Surface soil samples were taken in 1996 and 1997 from plots of corn (Zea mays L.), soybeans (Glycine max (L.) Merr.), oats (Avena sativa L.), or meadow (alfalfa) (Medicago sativa L.) that had received 0 or 180 kg N ha–1 before corn and an annual application of 20 kg P and 56 kg K ha–1. The Cmic and Nmic values were determined by the chloroform-fumigation-extraction method and the chloroform-fumigation-incubation method, respectively. The Cmic and Nmic values were significantly affected (P<0.05) by crop rotation and plant cover at time of sampling, but not by N fertilization. In general, the highest Cmic and Nmic contents were found in the multicropping systems (4-year rotations) taken in oats or meadow plots, and the lowest values were found in continuous corn and soybean systems. On average, Cmic made up about 1.0% of the organic C (Corg), and Nmic contributed about 2.4% of the total N (Ntot) in soils at both sites and years of sampling. The Cmic values were significantly correlated with Corg contents (r≥0.41**), whereas the relationship between Cmic and Ntot was significant (r≤0.53***) only for the samples taken in 1996 at the NERC site. The Cmic : Nmic ratios were, on average, 4.3 and 6.4 in 1996, and 7.6 and 11.4 in 1997 at the NERC and CWRC sites, respectively. Crop rotation significantly (P<0.05) affected this ratio only at the NERC site, and N fertilization showed no effect at either site. In general, multicropping systems resulted in greater Cmic : Corg (1.1%) and Nmic : Ntot (2.6%) ratios than monocropping systems (0.8% and 2.1%, respectively).

If the martian south polar cap were composed of solid carbon dioxide, would it be sufficiently stable against collapse under its own weight? This question is examined in the light of new experiments on the creep of solid carbon dioxide and new high-resolution topographic mapping of the south polar cap. The conclusion from a simple model is that, with the strongest of three flow laws compatible with the measurements, CO2 is strong enough to support a cap of this material with thickness about 1800 m for 107 years or more, which is the age suggested by the cratering record. However, none of the three possible flow laws will allow a 3000-m cap, the thickness suggested by stereogrammetry, to survive for 107 years, indicating that the south polar ice cap is probably not composed of pure CO2 ice.

The placenta is an immunologically unique organ where a balance between maternal immunity and fetoplacental well-being must be maintained for successful pregnancy to occur. The intervillous blood is important in this context, yet little is known about local immunologic processes, particularly how placenta-specific memory immune responses are maintained. Using malaria as an illustrative case, we describe an hypothetical model in which recirculation of memory T lymphocytes from the intervillous blood to local lymphoid tissue facilitates maintenance of local memory immunity. This explains how memory cells might be retained when the placenta is expelled at parturition and thus remain available for rapid recall from the local lymphoid tissue to the intervillous space when exposure to the same antigenic stimulus occurs in subsequent pregnancies. Study of cell-mediated immunity to infections like malaria in the intervillous blood and the use of animal models will be necessary to provide proof for this hypothesis. Copyright 2000 Harcourt Publishers Ltd

DNA target sites for a "multivalent" 11-zinc-finger CCTC-binding factor (CTCF) are unusually long ( approximately 50 base pairs) and remarkably different. In conjunction with the thyroid receptor (TR), CTCF binding to the lysozyme gene transcriptional silencer mediates the thyroid hormone response element (TRE)-dependent transcriptional repression. We tested whether other TREs, which in addition to the presence of a TR binding site require neighboring sequences for transcriptional function, might also contain a previously unrecognized binding site(s) for CTCF. One such candidate DNA region, previously isolated by Bigler and Eisenman (Bigler, J., and Eisenman, R. N. (1995) EMBO J. 14, 5710-5723), is the TRE-containing genomic element 144. We have identified a new CTCF target sequence that is adjacent to the TR binding site within the 144 fragment. Comparison of CTCF recognition nucleotides in the lysozyme silencer and in the 144 sequences revealed both similarities and differences. Several C-terminal CTCF zinc fingers contribute differently to binding each of these sequences. Mutations that eliminate CTCF binding impair 144-mediated negative transcriptional regulation. Thus, the 144 element provides an additional example of a functionally significant composite "TRE plus CTCF binding site" regulatory element suggesting an important role for CTCF in cooperation with the steroid/thyroid superfamily of nuclear receptors to mediate TRE-dependent transcriptional repression.

Abstract:  The impacts of crop rotations and N fertilization on different pools of arylsulfatase activity (total, intracellular, and extracellular) were studied in soils of two long-term field experiments in Iowa to assess the contibution of the microbial biomass to the activity of this enzyme. Surface-soil samples were taken in 1996 and 1997 in corn, soybeans, oats, or meadow (alfalfa) plots that received 0 or 180 kg N ha–1 before corn, and an annual application of 20 kg P ha–1 and 56 kg K ha–1. The arylsulfatase activity in the soils was assayed at optimal pH (acetate buffer, pH 5.8) before and after chloroform fumigation; microbial biomass C (Cmic) and N (Nmic) were determined by chloroform-fumigation methods. All pools of arylsulfatase activity in soils were significantly affected by crop rotation and plant cover at sampling time, but not by N fertilization. Generally, the highest total, intracellular, and extracellular arylsulfatase activities were obtained in soils under cereal-meadow rotations, taken under oats or meadow, and the lowest under continuous cropping systems.Total, intracellular, and extracellular arylsulfatase activities were significantly correlated with Cmic (r>0.41, P<0.01) and Nmic (r>0.38, P<0.01) in soils. The averages of specific activity values, i.e., of arylsulfatase activity of the microbial biomass, expressed per milligram Cmic, ranged from 315 to 407 μg p-nitrophenol h–1. The total arylsulfatase activity was significantly correlated with the intracellular activity, with r values >0.79 (P<0.001). In general, about 45% of the total arylsulfatase activity was extracellular, and 55% was associated with the microbial biomass in soils, indicating the importance of the microflora as an enzyme source in soils.

Three kornerupine occurrences are reported in distinctive SiO2-poor, MgO- and Al2O3-rich paragneisses from the Namaqualand Metamorphic Complex in South Africa. Kornerupine coexists stably with phlogopite, cordierite, orthopyroxene, gedrite, sapphirine, sillimanite and plagioclase and, in sapphirine-free rocks, with spinel and corundum. Tourmaline of a texturally older generation than kornerupine is commonly present in the same samples.

EnvironmentPreparing for the 21st Century. By Paul Kennedy, HarperCollins, London, 1993, 428 pp, £20.00, ISBN 0-00-215705-5 hbk, £7.99, ISBN 0-00-686-2985 pbk.Our Planet, Our Health. Report of the WHO Commission on Health and Environment, World Health Organization, Geneva, 1992, 282pp, Sw Fr 45.00, ISBN 92-4-156148-3.Facing the Future: Beyond the Earth Summit.By Johan Holmberg, Koy Thomson and Lloyd Timberlake Earthscan, London, 1993, 40pp, £4.95, ISBN 1-85383-154-9.Chemical weaponsBanning Chemical Weapons: The Scientific Background. By Hugh D Crone, Cambridge University Press, Cambridge, 1992, 122pp, hbk £27.95, IBSN 0-521-41699-X, pbk £8.95, ISBN 0-521-42711-8.Veterans at Risk: The Health Effects of Mustard Gas and Lewisite. Edited by Constance M Pechura and David P Rall, for the Committee to Survey the Health Effects of Mustard Gas and Lewisite, National Academy Press, Washington DC, 1993, 427pp, £29.95 (pbk), ISBN 0-309-04832-X.LandminesLandmines: A Deadly Legacy.The Arms Project of Human Rights Watch, and Physicians for Human Rights, New York and Boston, 1993, 528 pp, £20 from Housmans Bookshop, 5 Caledonian Road, London N1 9DX, ISBN 1-56432-113-4.SurgerySurgery and Society in Peace and War: Orthopaedics and the Organization of Modern Medicine 1880-1948. By Roger Cooter, Macmillan, London, 1993, 399 pp, £45.00, ISBN 0-333-55620-8.War Wounds of Limbs: Surgical Management. By Robin M Coupland, Butterworth Heinemann, London, 1993, 100 pp, ISBN 0-7506-1491-9.Psychology of violenceThe Insanity of Normality. Realism as Sickness: Toward Understanding Human Destructiveness. By Arno Gruen, translated from German by Hildegarde and Hunter Hannum, Grove Weidenfeld, New York, 1992, 226pp, $21.95, ISBN 0-8021-1169-6.

In short-cycle batch production processes difficulties are experienced in the direct measurement of temperature in high-viscosity fluid mixing environments. There is often a need to penetrate high shear flows with the sensor to ensure that measurements representative of bulk temperature are obtained. Significant measurement errors are experienced due to the temperature differential between the bulk of the fluid and the surface of the probe. The resulting strength requirements of probe supporting structures also contribute errors as a result of additional heat capacity and additional heat conduction paths from the sensors. This paper presents research towards the design of a multi-sensor probe integrated with computational algorithms devised to reduce these effects. Initial trials demonstrate that such schemes can be applied to reduce steady state errors and to improve response times over existing measuring devices.

Early Paleozoic metaturbidite-hosted Au-As-W-B mineralization, believed to be of a style previously unknown in southern Africa, has been discovered in the ensialic inland branch of the Pan-African Damara Orogen. A 2500-m-long zone of gold mineralization is hosted by altered Kuiseb Formation schist, quartz veins, and mylonite rocks in the aureole of a leucogranite and rare element pegmatite dome on the farm Sandamap Noord, west of Usakos, central Namibia. Au/As fluids either mobilized from the metasediments by and/or expelled from the stanniferous pegmatites and leucogranite were concentrated in NNE-trending Damaran D4 structures. Rb-Sr whole-rock dates and Pb-Pb model ages indicate that the gold mineralizing event occurred at 469-464 Ma. The three main types of alteration/mineralization are: a kaolinite-alunite rock (possibly advanced argillic alteration) that contains < 1 g/t Au, a jarosite schist that contains up to 46 g/t Au, and a massive grunerite rock that contains up to 0.5 g/t Au. Associated alteration includes a massive calcite-graphite-tourmaline rock and galena and pyrite-bearing quartz veins. Some of the high-strain zones surrounding the domal structure formed during the diapiric intrusion of the granites and pegmatites and are thus unrelated to the regional tectonism, but only the NNE-trending portions are mineralized with gold. The gold zone lies within 10 km of the NNE-trending Welwitschia lineament zone, which played an important role in the localization of late-/post-tectonic uraniferous alaskites at the Rossing Uranium Mine. The mineralization on Sandamap Noord shows certain similarities with Archean mesothermal gold deposits, being epigenetic, structurally controlled in late-tectonic structures, and having a Au-As-W association. The majority of turbidite-hosted gold deposits are hosted by dilational structures in greenschist-facies greywackes and slates. This discovery has shown that ductile and mylonitic structures in turbidite sequences that have been metamorphosed to upper amphibolite facies grade and been intruded by granitic intrusions are also prospective for gold.

AbstractQuartz-gahnite-sillimanite asssemblages are described from a supracrustal enclave at Kraaifontein, 45 km south-west of Springbok in the Namaqualand Metamorphic Complex, South Africa. The assemblage formed by prograde reaction in the granulite facies zone during the 1100 Ma Namaqua event, possibly as the result of desulphidation of sphalerite. Subsequent lower-amphibolite-facies retrogression occurred in close proximity to shear zones during an early Pan-African metamorphic event at 700 Ma. Zincian staurolite formed as overgrowths on gahnite in a hydration reaction involving the consumption of gahnite, quartz, and sillimanite. Compositional zoning to more zinc-rich rims in gahnite at Kraaifontein is unrelated to the retrograde reaction, but is interpreted as a result of changing conditions during the prograde Namaqua event.

The Elzevir batholith belongs to a suite of trondhjemitic intrusions emplaced at ca. 1,240 Ma in the Grenville Province of eastern Ontario. New major and trace element data, including REE, combined with isotopic and petrographic data indicate that:1)the batholith has calc-alkalic affinities;2)the Elzevir parental magma is very similar to that of dacites in the nearby, coeval metavolcanic rocks; the magma formed by partial melting of crustal material at granulite grade;3)chemical differences between the plutonic and volcanic rocks can be best explained by accumulation of plagioclase in the plutonic environment;4)fractionation was dominated by plagioclase and quartz, with lesser biotite and epidote, and minor zircon and apatite.

Examination of eroded and intact earth mounds in the Clanwilliam district, South Africa, indicates that they are well-established active termitaria of the harvester termite Microhodotermes viator. Unoccupied lower portions of the mounds contain ubiquitous trace-fossil evidence of earlier inhabitation by the same species. Previous studies indicating that fossorial molerats played a major role in the formation of the mounds are not supported by the observations presented here. Calcretization of the basal parts of the earth mounds has been caused by groundwater interaction with the more alkaline mound soil. 14C dating of this calcrete indicates that the earth mounds have been in existence for at least 4000 years, an order of magnitude greater than any previously recorded longevity for termitarium inhabitation.

The study of human malaria has been hampered by the lack of small animal models for the human-infecting malarial parasites. To approach this problem, the erythrocytic stages of the human malarial parasite Plasmodium falciparum were adapted to in vitro growth in the presence of ascites fluid from mice homozygous for the severe-combined immunodeficiency (scid) mutation. Human red blood cells (hRBCs) infected with these adapted parasites were then injected i.p. into nonobese diabetic scid/scid (NOD/LtSz-scid) mice. With daily supplemental intraperitoneal boosts of uninfected hRBCs, parasites were detected in the peripheral circulation of these mice for an average of 7 d after injection. Splenectomy of NOD/LtSz-scid mice increased both the level and duration of parasitemia in the periphery, and it also promoted the circulation of mature sexual stage parasites (gametocytes). When Anopheline mosquitoes were allowed to feed on the splenectomized mice, the gametocytes were ingested by the mosquitoes and developed into oocysts in the mosquito midguts. To our knowledge, these results are the first demonstration of human malarial parasite propagation in mice and transmission of these parasites to the invertebrate vector.

Dynamical modelling techniques are presented that facilitate the derivation of transfer function models between key inputs and outputs of internal mixing processes. Tests to model the mastication of natural rubber in a Francis Shaw Intermix at two levels of fill-factor are described. The derived models will form the basis for closed-loop control strategies.

THE Archaean–Proterozoic boundary, it has been suggested, marks a fundamental change in the behaviour of the Earth, ending an early phase of cratonisation and the beginning of a period characterised by stable shelf sedimentation and linear orogens1,2,3. Almost all Archaean terrains, other than those dominated by granulites and migmatites, seem to be characterised by a variety of granitoid rocks intimately associated with ultramafic through mafic to calc-alkalic sequences, and their sedimentary associations. These greenstone belt assemblages are remarkably similar from one craton to another; they are usually folded into keel-shaped troughs, subjected to greenchist facies metamorphism and usually show similar structural styles which suggest that they were acted on by predominantly vertical forces. Their alleged antiquity (2,000 Myr or more) and widespread distribution have been attributed to either a change in the geothermal gradient as the Earth became colder3or the existence of a relatively thin, Archaean, continental crust4,5.

The topography provided by altimetry, synthetic aperture radar‐topography, and stereo radargrammetry has opened new doors for Titan research by allowing for quantitative analysis of morphologic form. Using altimetry measurements, we show that Titan's Maria are consistent with an equipotential surface but that several filled lakes are found to be hundreds of meters above this sea level, suggesting that they exist in isolated or perched basins. Within a given drainage basin, empty lake floors are typically higher than the liquid elevation of nearby lakes/seas, suggesting local subsurface connectivity. The majority of Titan's lakes reside in topographically closed, sharp‐edged depressions whose planform curvature suggests lateral expansion through uniform scarp retreat. Many, but not all, empty lake basins exhibit flat floors and hectometer‐scale raised rims that present a challenge to formation models. We conclude that dissolution erosion can best match the observed constraints but that challenges remain in the interpretation of formation processes and materials. From a combination of topographic techniques, we show that the liquid elevations of Titan's seas are consistent with an equipotential surface (similar to Earth's oceans). The same measurements show that Titan's small lakes can be found several hundreds of meters above the sea level, suggesting that they are potentially isolated from the seas. Within a given watershed, however, nearby lakes show evidence for local connectivity. Using the same topographic data set, we examine the topographic profile of Titan's filled and empty lake depressions. The depressions have flat floors and hundred‐meter scale raised rims that present a challenge to understanding their formation. We conclude that dissolution erosion (e.g., karst on Earth) can best match the observed constraints but that challenges still exist in the interpretation of formation processes and materials. Titan's seas are consistent with an equipotential surfaceThe liquid elevation of Titan's lakes can be found hundreds of meters above the seasLakes reside in topographically closed, sharp‐edged depressions. Many have raised rims that are hard to reconcile with formation models