Positive Relief Research Articles

Impact History of Eros: Craters and Boulders

Preliminary measurements of craters and boulders have been made in various locations on Eros from images acquired during the first nine months of NEAR Shoemaker's orbital mission, including the October 2000 low altitude flyover. (We offer some very preliminary, qualitative analysis of later LAF images and very high-resolution images obtained during NEAR's landing on 12 February 2001). Craters on Eros >100 m diameter closely resemble the saturated crater population of Ida; Eros is more heavily cratered than Gaspra but lacks the saturated giant craters of Mathilde. These craters and the other large-scale geological features were formed over a duration of very roughly 2 Gyr while Eros was in the main asteroid belt, between the time when its parent body was disrupted and Eros was injected into an Earth-approaching orbit (probably tens of Myr ago). Saturation equilibrium had been expected to shape Eros' crater population down to very small sizes, as on the lunar maria. However, craters <200 m diameter are instead progressively depleted toward smaller sizes and are a factor of ∼200 below empirical saturation at diameters of 4 m. Conversely, boulders and positive relief features (PRFs) rise rapidly in numbers (differential power-law index ∼−5) and those <10 m in size dominate the landscape at high resolutions. The pervasive boulders and minimal craters on Eros is radically different from the lunar surface at similar scales. This may be partly explained by a major depletion of meter-scale projectiles in the asteroid belt (due to the Yarkovsky Effect: Bell 2001), which thus form few small craters and destroy few boulders. Additionally, the small size and low gravity of Eros may result in redistribution or loss of ejecta due to seismic shaking, thus preferentially destroying small craters formed in such regolith. Possibly Eros has only a patchy, thin regolith of mobile fines; the smaller PRFs may then reflect exposures of fractured bedrock or piles of large ejecta blocks, which might further inhibit formation of craters <10 m in size. Eros may well have been largely detached dynamically and collisionally from the main asteroid belt for the past tens of Myr, in which case its cratering rate would have dropped by two orders of magnitude, perhaps enhancing the relative efficacy of other processes that would normally be negligible in competition with cratering. Such processes include thermal creep, electrostatic levitation and redistribution of fines, and space weathering (e.g., bombardment by micrometeorites and solar wind particles). Combined with other small-body responses to impact cratering (e.g., greater widespread distribution of bouldery ejecta), such processes may also help explain the unexpected small-scale character of geology on Eros. If there was a recent virtual hiatus in cratering of Eros (during which only craters <∼300 m diameter would be expected to have formed), space weathering may have reached maturity, thus explaining Eros' remarkable spectral homogeneity compared with Ida.

Seepage meters and Bernoulli’s revenge

Evaluation of seepage data from a network of 50 permanently deployed submarine seepage meters, specially construc ted from fiberglass, indicates that the devices artificially advect (Bernoulli effect) shallow ground water. Reverse flow into the rock was not observed even when adjacent piezometers installed 2-m to 20-m below the rock-water interface in dicated negative groundwater heads. Quantitative testing of five different designs, including conventional end-of-oildrum designs, indicates that meters presenting positive relief on the sea floor are subject to the Bernoulli effect when placed in areas where there are waves and/or currents. Advection does not appear to be caused by flexing of the collection bags.

New Data on the Cenozoic History of the Underwater Yamato Rise, Sea of Japan

The Miocene terrestrial plant assemblage (in macro- and microfossils) from the underwater Yamato Rise (Sea of Japan) is examined. A fossil leaf found in the tuffogenic–sedimentary strata is identified as belonging to the beech tree. Data on the Paleogene–Neogene history of the underwater rise are given. Against the background of its general subsidence, positive relief features (volcanoes and their formations) were formed. During the Cenozoic, the entire Sea of Japan depression experienced a submergence.

Detrital fission track thermochronology of Upper Cretaceous syn‐orogenic sediments in the South Carpathians (Romania): inferences on the tectonic evolution of a collisional hinterland

ABSTRACT The tectonic evolution of a collisional hinterland sourcing the Ha?eg Basin, a Late Cretaceous syn‐orogenic sedimentary basin in the South Carpathians (Romania), is revealed through fission track thermochronology of detrital apatite and zircon grains. This basin formed on the upper plate (Getic unit) in response to Late Cretaceous collision with the lower plate (Danubian unit), an allochtonous continental block of the Moesian Platform, upon closure of a narrow oceanic basin (Severin Basin). The fission track results suggest that Turonian to lower Maastrichtian sediments of the Ha?eg Basin have been dominantly derived from pre‐Late Cretaceous sources. The age components they contain relate to pre‐Cretaceous tectonothermal events such as the Variscan orogenic cycle, Jurassic rifting and Severin Basin formation, and to Early Cretaceous compressional tectonics. These results are compatible with the tectonic evolution of the upper plate that is identified as the primary source. From the onset of sedimentation (late Albian) until the early Campanian the Ha?eg Basin resembles a piggy‐back basin formed on the upper plate concomitant with underthrusting and internal stacking of the lower plate. In contrast, important tectonic subsidence during the late Campanian and early Maastrichtian reflects a shift to extensional tectonics causing the unroofing of the collision zone and the exhumation of lower plate rocks back to the surface. Our fission track data place important constraints on the timing of lower plate erosion that must have commenced during the late Maastrichtian, as documented by the completely reset Late Cretaceous age component within upper Maastrichtian sediments (Sînpetru Formation). Late Maastrichtian uplift of the basin and the formation of positive relief at the site of the collision zone is an expression of continuous convergence. The mismatch between the amount of denudation and the amount of sediments trapped in the Ha?eg Basin underlines the importance of concomitant extensional unroofing.

Tumuli and associated features from the western Deccan Volcanic Province, India

Whale-back-shaped uplifts called "tumuli" are common in the pahoehoe flows of the western Deccan Volcanic Province (DVP). Although they usually occur in hummocky flows, they are also associated with thicker sheet lobes. They have been subjected to a detailed morphometric and petrographic study for the first time. The tumuli are characterised by positive relief and "lava-inflation clefts" occupied by squeeze-ups. They display elongate as well as equant forms; some are constituted of a single flow lobe, whereas others display multiple flow lobes. Some tumuli appear to have developed along anastomosing tube systems. The detailed study of one of the tumuli reveals considerable petrographic and textural variations among the constituent flow units. Some of these, such as the enrichment of phenocrysts in squeeze-ups and breakouts, could be related to the emplacement dynamics of the tumulus. All the observed tumuli display much evidence of inflation or endogenous growth. Field observations and measurements reveal that the tumuli and associated pahoehoe features display a close similarity with their Hawaiian counterparts. This is a very significant observation since it points out to a similarity in nature and style of eruptions in Hawaii and at least in the western part of the DVP. This has an important bearing on determining the short, medium and long-term effusion rates in the Deccan; however, any concrete inference will have to await systematic volcanological studies of the lava features in the DVP.

Combined arthroscopic TFCC debridement and wafer resection of the distal ulna in wrists with triangular fibrocartilage complex tears and positive ulnar variance.

Because a certain percentage of patients with positive ulnar variance experience incomplete pain relief after triangular fibrocartilage complex (TFCC) debridement alone, we prospectively evaluated the feasibility and efficacy of combining arthroscopic TFCC debridement with arthroscopic wafer resection in such wrists as part of the same surgical procedure. We enrolled 12 patients between July 1998 and July 2000 and performed both subjective and objective assessment at follow-up with a minimum of 6 months and an average of 14 months. Seven posttraumatic and 5 degenerative tears were identified. Preoperative ulnar variance with a pronated grip x-ray averaged 2 mm and ranged between 1 and 4 mm. At final review 8 patients experienced complete pain relief and 4 experienced only minimal symptoms. The ulnocarpal stress test failed to elicit pain in any wrist. Nine patients were very satisfied, and 3 were satisfied. Grip strength improved 8 kg (36%). This procedure should be considered in the treatment of ulnar wrist pain when TFCC tears and positive ulnar variance coexist.

Late Weichselian glacimarine depositional processes in the southern Skagerrak revealed by high-resolution seismic facies analysis

Thirty kilometres of high-resolution, seismic-reflection (boomer) data were collected in the Skagerrak area, between Norway, Sweden and Denmark, to reconstruct the seismic stratigraphy in an area of late Weichselian shelf–margin progradation. By the use of lap-out style, five depositional units, A–E, were recognised in the boomer profiles. No stratigraphic control was available, but tentative correlation has been made on the basis of previous studies in the region. Unit A is interpreted as till. In unit B, the seismic facies association includes shingled, mounded, oblique channel fill, and parallel-bedded reflection configurations, which are interpreted to have formed in a channelled, proximal, pro-glacial environment. In unit C, discrete mounds and semi-continuous lensoid bodies with divergent channelled flow style constitute the facies association, and are interpreted predominantly as debris-flow deposits that accumulated in a distal pro-glacial environment. In unit D, the facies association constitutes mounds and oblique in-fill between mounds; positive relief and the distribution of facies shows that the deposits were laid down under the influence of a unidirectional current. Units B–D are interpreted as late Weichselian in age. Unit E is interpreted as the Holocene marine cover of laminated clay to fine sand. This seismic–stratigraphic succession reveals a high-resolution record of late Weichselian deglaciation in this area.

Debris flow and slide deposits at the top of the Internal Liguride ophiolitic sequence, Northern Apennines, Italy: A record of frontal tectonic erosion in a fossil accretionary wedge

Abstract In the Northern Apennines, the Internal Liguride units are characterized by an ophiolite sequence that represents the stratigraphic base of a late Jurassic–early Paleocene sedimentary cover. The Bocco Shale represents the youngest deposit recognized in the sedimentary cover of the ophiolite and can be subdivided into two different groups of deep sea sediments. The first group is represented by slide, debris flow and high density turbidity current‐derived deposits, whereas the second group consists of thin‐bedded turbidites. Facies analysis and provenance studies indicate, for the former group, small and scarcely evoluted flows that rework an oceanic lithosphere and its sedimentary cover. We interpret the Bocco Shale as an ancient example of a deposit related to the frontal tectonic erosion of the accretionary wedge slope. The frontal tectonic erosion resulted in a large removal of materials, from the accretionary wedge front, that was reworked as debris flows and slide deposits sedimented on the lower plate above the trench deposits. The frontal tectonic erosion was probably connected with subduction of oceanic crust characterized by positive topographic relief. This interpretation can be also applied for the origin of analogous deposits of Western Alps and Corsica.

Early Mesozoic (?Triassic) Landscapes in Australia: Evidence, Argument, and Implications

Australia has strong claims to be known as the old continent. In addition to landscapes of later Cretaceous–early Tertiary derivation, remnants of early Mesozoic (Triassic‐Jurassic) surfaces, which are part of the contemporary landscape, are also recognized. Being of etch type, they have two ages: one referring to the period of preparation by subsurface weathering and the other to their date of exposure. In many instances, exposure can be dated and the period of preparatory weathering closely inferred. Such old paleosurfaces are demonstrated on Kangaroo Island and are strongly implied in, for example, the Flinders, Gawler, and MacDonnell Ranges; in Arnhem Land and the Arcoona Plateaus; in many parts of the Eastern Uplands; and on several bornhardts in the Yilgarn and Gawler Cratons. They reinforce the suggestion that once in positive relief and shedding water, surfaces persist with little change for long periods. Such ancient features are incompatible with several well‐known models of landscape evolution. The chronologies and events they imply extend our understanding of the landscape in the chronological context. They add to our knowledge of Earth's history.

Mud volcanoes in deepwater Nigeria

Detailed study of 3D seismic data from deepwater Nigeria has revealed the presence of features interpreted to be mud volcanoes. They occur in an upper slope environment seen as 1–2 km circular features at the seabed. Seabed cores from the mud volcanoes contain oil, gas and sand/shale–clast content richer than the seabed background. Pliocene fossils have been identified in the cores, demonstrating transport of material from depth. The features show a high seabed seismic amplitude above a chimney of chaotic seismic reflections and data wipe-out. The mud volcanoes in the study area shows two distinct clusters located over deeper structural culminations. Four active mud volcanoes (Area 1) are located above a rollover anticline in the central part of the area. Cuspate listric faults reach the seabed on the up-slope side of these mud volcanoes. Four abandoned mud volcanoes have also been identified, with progressively older ages towards the crest of the underlying structure. These abandoned features are associated with an extremely chaotic seismic signature. A combination of over-pressured carrier beds and low integrity top seals are believed to be responsible for the formation of these mud volcanoes. It is further believed that gas expansion, subsequent to seal failure, was the main driving force for what must have been violent eruptions. The long lived mud volcano activity over the deep structural closure suggests a plumbing system that focuses on escaping compaction water and hydrocarbons through time. In the south west of the study area, another cluster of five mud volcanoes is located above a shale diapir. The seabed expression of the members of this cluster is more varied. Some show a positive relief at the seabed while others show circular depressions. The largest feature represents an assemblage of many smaller mud volcanoes with a common root system. Their seismic expression is also different from that of Area 1, with a well-defined sediment wedge at surface and a shallower root system. These features are believed to represent a less violent type of mud volcano characterised by ductile flow. Tectonic stress, due to growth of the underlying diapir, is thought to have played an important role during eruption, in addition to focused methane escape and the low mechanical strength of the overburden.

Bulge Migration and Pinnacle Reef Development, Devonian Appalachian Foreland Basin.

Detailed stratigraphic analyses of Late Emsian and Early Eifelian (Lower to Middle Devonian) carbonate-dominated strata in the northern Appalachian Basin indicate anomalous, locally varying relative sea level changes and inversions of topography. The distribution of a major basal-bounding unconformity, basinal pinnacle reefs, local absence of parasequences, and eastward migration of shallow marine carbonate lithofacies and related biofacies in the Onondaga Limestone and underlying strata mark the retrograde migration of an elongate, northeast-southwest-trending area of positive relief, bordered on its cratonward side by a similarly migrating basin of intermediate depth. These features are thought to represent the forebulge and back-bulge basin of the Appalachian foreland basin system as it developed during a time of relative quiescence within the Acadian Orogeny. However, the relatively small size of the bulgelike feature (ca. 80-100-km-wide, 20-50-m positive relief), its great distance from the probable deformation front (>400 km), and the lack of a well-developed foredeep immediately adjacent to the bulgelike feature may indicate that it represents a smaller-scale flexural high ("flexural welt") superposed over the cratonward edge of the larger-scale classical forebulge of the basin. Development of shallow-water reefs on the crest of the bulge during sea level lowstand, followed by migration of the bulge and widespread transgression, permitted growth of economically significant pinnacle reefs in the deep basin center. Further subsurface reef exploration should concentrate along the projected position of the bulge during the basal Onondaga lowstand.

Rapid prototyping of microfluidic switches in poly(dimethyl siloxane) and their actuation by electro-osmotic flow

This paper describes a procedure for rapidly and conveniently prototyping microfluidic devices that are useful with aqueous solutions. A design (with diameters of channels 20 µm) is created in a computer-aided design program and printed at high resolution on a transparency. This transparency is used as a mask in photolithography to create a master in positive relief photoresist: casting poly(dimethyl siloxane) (PDMS) against this master yields a polymeric replica containing a network of bas-relief channels. The channels are closed and sealed irreversibly by oxidizing the replica and another flat substrate (PDMS, glass, silicon, silicon oxide) in an oxygen plasma and bringing the two surfaces into conformal contact. Oxidation of the polymer allows the formation of a seal without using adhesives; it also generates channels that support electro-osmotic flow (EOF) and fill easily with aqueous solutions. Two microfluidic devices - a fluidic switch and a side channel flow controller - have been fabricated using this rapid prototyping methodology. These devices were tested using aqueous solutions as the test fluid and actuated by EOF.

The schizophrenia Algorithm

Back to table of contents Previous article Next article LetterFull AccessThe schizophrenia AlgorithmJohn A. Chiles, M.D., and Alexander Miller, M.D.John A. ChilesSearch for more papers by this author, M.D., and Alexander MillerSearch for more papers by this author, M.D.Published Online:1 May 1999https://doi.org/10.1176/ps.50.5.703bAboutSectionsView EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail In Reply: We thank Drs. Berman and Fleishman for their comments, and note with interest that their letters define the spectrum of questions about clozapine: is it a first-line medication, or the drug of last resort? First, to consider Dr. Berman's question: clozapine has the best outcome data; why not use it first?In the schizophrenia algorithm of the Texas Medication Algorithm Project (TMAP), all roads lead to clozapine. Our rationale for this course is contained on pages 34-35 of our physicians' manual (1), available on the Internet (2). In brief, improvement in negative symptoms, clozapine's strong point, is a complex event perhaps involving positive symptom relief, the absence of extrapyramidal symptoms, and the absence of depression. This result may be achieved by other medications with side-effect profiles generally thought to be more benign than that of clozapine. In the TMAP algorithm, the response to other medications is evaluated in six to eight weeks, a period far shorter than the three to six months it takes to evaluate response to clozapine. If clozapine does not work, stopping it can be arduous, often producing a worsening of psychosis. Crossover is probably easier with other medications.The TMAP algorithm contains criteria for improvement that are more stringent than those used in the seminal clozapine study (3) and, to the best of our knowledge, are the most stringent criteria yet developed describing acceptable response (Miller A, Chiles J, Chiles J, et al, unpublished paper, 1999). In the TMAP algorithm, patients who do not improve to the extent that they have only mild symptoms in a few areas will move on to the clozapine stage.Having said that, we remain most interested in evaluating clozapine as a first-line drug. We are aware that a large study in China is currently evaluating this question (Lieberman J, personal communication, 1999). The TMAP schizophrenia algorithm is a dynamic instrument that has been revised four times in three years. As our knowledge expands, we expect future revisions.Dr. Fleishman asks if we enter patients into the algorithm who are doing well on their current regimen: we do not. Patients are entered only if their physician decides to change medication, a decision based on either symptoms or side effects. As to why clozapine is listed at stage 5 as an option before a combination of medications is tried, we believe the current literature best supports this monotherapy approach. We are quite aware of the increasing case-report literature on combinations of antipsychotics, and, as noted above, the algorithm can change.Last, as use of the TMAP algorithm increases, we have found a different issue with clozapine to be perhaps more pertinent: physicians are reluctant to use it, even when their patients have an inadequate response to other treatments. The reasons are not clear, but dread of agranulocytosis seems to be at the forefront. Some percentage of patients with schizophrenia—in our estimation, 10 percent—should be on clozapine. We are aware of a variety of databases that show usage to be nowhere near that level. Physicians themselves need to advocate the use of this drug.

Free-Phase NAPL-Trapping Features in Intermontane Basins

Just as free-phase oil and gas are trapped in the subsurface, spilled nonaqueous phase liquids (NAPLs) can be trapped or pooled by decimeter- to hectometer-scale features at contaminated sites. Free-phase NAPL is that which is sufficiently saturated to flow as a body in the subsurface. In order to trap free-phase NAPLs, the height of the trapping feature (trap-closure height) must be greater than the capillary intrusion of water into the NAPL phase, and the trap boundary must be sufficiently fine-grained to prevent the NAPL from entering its pores. Capillary intrusion of water into a free-phase NAPL body is a function of the physical properties of the liquid phases as well as the grain size within the trap, and it can be estimated using Hobson9s formula. Calculations suggest that necessary trap-closure heights are on the order of one to several centimeters for coarse-grained material and range from one to more than five meters for fine-grained sands. Features in intermontane basins with centimeter- to meter-scale positive or negative topographic relief may form environmentally significant free-phase NAPL traps. These include alluvial-fan, fluvial, lacustrine, eolian, and spring-related (krene-genic) deposits and the contacts between them as well as biogenic, pedogenic, volcanic, and tectonic features. Examples of possible free-phase light non-aqueous phase liquid (LNAPL) traps include buried channels, natural levees, gravel bars, gilgai (swelling clay hummocks), spring mounds, eolian and base-surge dunes, and eolian wedges adjacent to fault scarps. Examples of possible free-phase dense nonaqueous phase liquid (DNAPL) traps include scoured channel bases, incised and backfilled arroyos, deformed soft sediments, larger root traces and animal burrows, buried interdune areas, volcanic collapse features, and rotated wedges of sediments adjacent to faults. High-resolution noninvasive geophysical techniques promise to delineate subsurface strata at adequate scales to show features capable of trapping free-phase NAPL at contaminated sites. However, knowledge of geosystem permeability, migration pathways, and free-phase NAPL trapping processes may be needed to guide remediation efforts.

Reservoir Implications of Modern Karst Topography

Tropical karst landscapes exhibit a predominance of positive relief features relative to the negative relief features (i.e., sink holes, dolines, etc.) of temperate karst areas and yet, paradoxically, have never been observed in the subsurface on seismic sections. To understand why this is the case, topographic profiles were made over the positive karst relief features of China, Java, and Jamaica and were used to construct synthetic seismic sections. The results indicate that in most instances the magnitude of the topographic relief is sufficient to be seen on seismic sections. A possibility of misinterpreting karst highs as reefs seems clear, but more important in explaining the paradox is the fact that the magnitude of modern karst relief expression is largely attributable to uplift over an extended period. The probability of preservation of these positive relief solution residuals is dependent on the karstification process being aborted by the deposition of overlying sediment, an event not likely to occur in an uplift area. Uplift of well-lithified carbonate minimally results in an areally extensive runoff surface that controls the development of positive karst landforms. Uplift also commonly induces faulting and fracturing that further control the distribution of karst land forms. Hydrocarbon production from the resulting karst is geared to matrix porosity: the higher the matrix porosity, the greater the rate of deliverability of matrix oil to produced fracture and karst conduit oil. In contrast, the lowering of the base level of erosion due to a fall in sea level is generally less than that induced by uplift and, consequently, minimizes positive karst relief development relative to that of uplift. Subaerial exposure induced by passive sea level fall also minimizes the potential for the related occurrence of fracturing and faulting, which of itself mitigates against the general development of positive karst relief. The subaerial consequences of passive sea level fall are commonly preserved in the geologic record and result in karst reservoirs dominated by extensive moldic and vuggy porosity interconnected by solution channels. These reservoirs lack the production problems commonly attending fractured karst reservoirs with little matrix porosity.

Banff Field, UK Central Graben – evaluation of a steeply dipping, fractured chalk reservoir

The Banff Field is a steeply dipping raft of fractured Late Cretaceous and Danian chalk on the flank of a salt diapir structure on the western margin of the Central Graben in the UK North Sea. Paleocene sands draped over the raft and a carbonate cap rock provide additional reservoir potential. The unusual geometry of the reservoir is a result of a complex structural history. Generally positive relief and minor pulsed growth through the Cretaceous and Lower Tertiary resulted in a condensed sequence of Cretaceous and Tertiary sediments over the structure. Contractional rejuvenation and active diapirism in the mid-Miocene deformed and fractured the thinned overburden to produce a tilted raft with reservoir dips generally over 45°. A vertical oil column of over 950 m (3000 ft) is present. Hydrocarbon migration began during the Oligocene, preserving good porosity in the chalk matrix during subsequent Late Miocene burial. Seismic imaging difficulties caused by the steep dips and uncertainties over reservoir performance and connectivity led to a phased development plan. Phase 1 involved a six month early production system (EPS) via two imaginatively designed production wells, during which time 5 × 10 6 BBL oil were produced. The two wells were drilled from the crest of the raft down to the oil water contact. Each well encountered over 1000 m (3300 ft) of oil-bearing chalk reservoir and provided important geological and reservoir performance data. Seismic data have been reprocessed using 3D pre-stack depth migration to improve image quality and lateral positioning. Geophysical, geological and biostratigraphical data have been integrated with the dynamic performance from the EPS to assess the controls on reservoir quality. The bulk of the reserves, and highest productivity occur in the Late Cretaceous Tor Formation. Chalk porosity ranges from 15–35% but matrix permeabilities are low, generally less than 5 mD. High productivities (up to 40 000 BOPD) achieved during the EPS are attributed to specific zones within the Tor chalks which have a favourable combination of chalk lithofacies (including local reworking to produce chalk debris flows), open fractures, depth of burial, diagenetic history and stratigraphy. Sand units within the Ekofisk chalk may have a significant impact on fluid flow. In situ stress is expected to exert a major (favourable) influence on waterflood performance. An effective phased development programme has resulted in an improved understanding of the complex controls on chalk reservoir performance in preparation for Phase 2 development. First oil is planned for mid-1998 and ultimate reserves are expected to be in excess of 60 × 10 6 BBL oil.

Dinosaur skin impressions and associated skeletal remains from the upper Campanian of southwestern New Mexico: new data on the integument morphology of hadrosaurs

ABSTRACT Skin impressions from the tail region of an indeterminate hadrosaur recently excavated from the Upper Cretaceous Ringbone Formation, southwest New Mexico represent the first known dinosaur specimen from New Mexico with impressions of the integument preserved in association with skeletal remains. The mid- to distal-caudal region is represented by 20 articulated centra, other disarticulated centra, a single chevron, ossified tendons and fragmentary bone, including poorly preserved neural spines. The skin impressions are preserved in negative and positive relief between two very fine-grained sandstone beds, interpreted as part of a fluvio-lacustrine facies package. The impression surface is directly below the ossified tendons, and 2.5 m from the articulated vertebral column. The skin impressions are six discrete patches characterized by predominantly apical, circular to ovate tubercles. Measurements of the long and short axes of individual tubercles demonstrate that a distribution of relatively homogenous tubercle sizes occur along the tail section. The tubercles range from 3 to 12 mm and 10 to 16 mm on the short and long axes, respectively. All tubercles examined are ornamented with radiating ridges and grooves that converge at their apex. Presently, the material cannot be identified below the level of Hadrosauridae; however, a comparison of tubercle size, shape and ornamentation described previously from hadrosaur skin impressions indicates the integument morphology of the Ringbone hadrosaur has some similarities to that of the gryposaurs. In general, the complexity of the radial sculpturing, specifically the number of ridges and rugosity, increases with increasing tubercle size. This specific type of ornamentation is not known from modern reptiles or birds; however, the tubercular morphology is similar to that of the lizard Heloderma. Although it is impossible to determine whether the ridges and grooves may have had a physiologic function, these features would increase the surface area of the skin, and therefore may have afforded more efficient heat exchange across the skin, or possibly provided added resistance to tearing and puncturing.

Rapid Prototyping of Microfluidic Systems in Poly(dimethylsiloxane)

This paper describes a procedure that makes it possible to design and fabricate (including sealing) microfluidic systems in an elastomeric material [Formula: see text] poly(dimethylsiloxane) (PDMS) [Formula: see text] in less than 24 h. A network of microfluidic channels (with width >20 μm) is designed in a CAD program. This design is converted into a transparency by a high-resolution printer; this transparency is used as a mask in photolithography to create a master in positive relief photoresist. PDMS cast against the master yields a polymeric replica containing a network of channels. The surface of this replica, and that of a flat slab of PDMS, are oxidized in an oxygen plasma. These oxidized surfaces seal tightly and irreversibly when brought into conformal contact. Oxidized PDMS also seals irreversibly to other materials used in microfluidic systems, such as glass, silicon, silicon oxide, and oxidized polystyrene; a number of substrates for devices are, therefore, practical options. Oxidation of the PDMS has the additional advantage that it yields channels whose walls are negatively charged when in contact with neutral and basic aqueous solutions; these channels support electroosmotic pumping and can be filled easily with liquids with high surface energies (especially water). The performance of microfluidic systems prepared using this rapid prototyping technique has been evaluated by fabricating a miniaturized capillary electrophoresis system. Amino acids, charge ladders of positively and negatively charged proteins, and DNA fragments were separated in aqueous solutions with this system with resolution comparable to that obtained using fused silica capillaries.

Energy and moisture considerations on cutover peatlands: surface microtopography, mulch cover and Sphagnum regeneration

This study examined (i) the effect of artificially created microtopography and straw mulch on the soil moisture and (ii) energy balance and the establishment of a Sphagnum cover on a cutover peatland. Straw mulch caused rainfall interception approaching 2 mm per event. Although interception represented 44% of the total rainfall over the measurement period, water that evaporated from the mulch used energy that would otherwise have been used to evaporate soil water. Thus, the net effect of interception by mulch was negligible. The soil heat flux below the mulch was only 13% of the bare soil value and was decoupled from the daily net radiation. Net radiation over the bare soil was 15% greater than over the mulch. However, because of the greater heat flux into the bare peat, the energy available for sensible and latent heat fluxes was similar between the mulch covered and bare peat. Average evaporation from mulch and bare soil was estimated to be 2.6 and 3.1 mm d −1, respectively. Soil water tension 1 cm below the surface remained above −100 cm (mb) all season (100% of the time) when a mulch was used, compared to only 30% of the time in the bare soil. Correspondingly, the water table was sustained above the 40 cm depth, 60% of time in the mulch covered site, compared to only 40% of the time in the bare peat site. Negative relief elements of the microtopography were wetter and cooler than positive relief elements. However, when under a mulch, the negative relief elements provided no additional benefit, in terms of temperature or soil moisture amelioration. The control site with a mulch cover was equivalent or better than negative relief elements with a mulch cover. Taking into account the poorer performance of positive relief elements, even when mulch covered, the creation of surface microtopography reduced the overall moisture content of the site. Sphagnum established and spread only when the diaspores were protected with a straw mulch. All microtopography types tested had no effect on the establishment of Sphagnum mosses when the microtopography treatments, including positive and negative relief elements, were treated as a whole, although being in a depression helped Sphagnum establishment.

The descriptive nomenclature and classification of growth fabrics in fossil scleractinian reefs

Framework (sensu stricto) is a concept originally relating to modern reefs and is defined by structural, ecological and sedimentological criteria. However, in the geological literature the term `framework' has come to be applied to almost any organically influenced in situ accumulation, including non-calcareous, non-rigid facies associated with sea grasses. This drastic departure from the original meaning is misleading and scientifically unhelpful. The concept of wave resistance is integral to that of framework, but in the geological record it is not easy to evaluate and the term may be of little comparative use between reef environments. It is suggested that the term growth fabric be generally applied as a descriptive term for the presence of aggregated in situ corals (or other organisms) in growth position within a facies. The term growth fabric should be used as an alternative to `framework' as a purely descriptive term. The term framework should be restricted to its original definition and used only where the criteria for framework can be clearly demonstrated. Two end-member types of scleractinian growth fabric genesis are recognised, termed superstratal and constratal (terms adapted from Gili, E., Masse, J.P., Skelton, P.W., 1995. Rudists as gregarious sediment-dwellers, not reef-builders, on Cretaceous carbonate platforms. Palaeogeogr., Palaeoclimatol., Palaeoecol. 118, 245–267). In a superstratal growth fabric, the constituent organisms collectively projected decimetres to metres above the substratum creating positive topographic relief. In contrast, constratal growth is where vertical organic accretion occurred at a similar rate to sediment accumulation; hence the majority of the skeletal material remained continuously embedded in the sediments, and only a small proportion of the skeleton projected (centimetres) above the sediment surface. The architectural, palaeoecological, sedimentological and diagenetic implications of different types of growth fabric genesis is discussed. A review of the classification of reef fabrics suggests that there is currently no adequate system to describe fossil scleractinian growth fabrics. The most commonly used classification of reefal fabrics is that of Embry and Klovan (1971). [Embry, A.F., Klovan, J.E., 1971. A Late Devonian reef tract on northeastern Banks Island, Northwest Territories. Bull. Can. Pet. Geol. 33, 730–781.] There are a number of shortcomings in this scheme which may be grouped into three categories: (1) the interpretative nature of the classification; (2) problems in interpreting biological effect from form; and (3) insufficient categories to adequately describe Mesozoic and Cenozoic growth fabrics. Moreover, there appears to be a lack of a standardised nomenclature for growth fabrics which has hindered meaningful comparisons of scleractinian growth fabrics through time and space. A descriptive system based on a modification and expansion of the Embry and Klovan system (1971) is proposed and a revised nomenclature for growth fabrics presented. The system is designed to be flexible in its application — it can be used simply to describe a growth fabric, or, through the use of genetic and non-genetic modifiers, to imply types of reef-building processes and growth fabric heterogeneity. Although the concepts and terminology discussed in this paper relate to scleractinian growth fabric, they are equally applicable to fabrics comprising other organisms.