bluuebunny/crossref_metadata_2025 huggingface dataset:
Oligocene-Miocene middle crustal flow in southern Tibet: geochronology of Mabja Dome
Authors: Lee J. , McClelland W. , Wang Y. , Blythe A. , McWilliams M.
Published: April 2008

New U-Pb zircon, monazite,
40
Ar/
39
Ar, and apatite fission track ages provide constraints on the timing of formation and exhumation of the Mabja Dome, southern Tibet, shed light on how this gneiss dome formed, and provide important clues on the tectonic evolution of middle crustal rocks in southern Tibet. Zircons from a deformed leucocratic dyke swarm yield a U-Pb age of 23.1 ± 0.8 Ma, providing the first age constraint on the timing of middle crustal ductile horizontal extension in the North Himalayan gneiss domes. Zircons and monazite from a post-tectonic two-mica granite yield ages of 14.2 ± 0.2 Ma and 14.5 ± 0.1, respectively, indicating that vertical thinning and subhorizontal stretching had ceased by the middle Miocene. Mica
40
Ar/
39
Ar ages from schists and orthogneisses increase structurally down-section from 12.85 ± 0.13 Ma to 17.0 ± 0.19 Ma and then decrease at the deepest structural levels to 13.29 ± 0.09 Ma. Micas from the leucocratic dyke swarm and post-tectonic two-mica granites yield similar
40
Ar/
39
Ar cooling ages of 13.48 ± 0.13 to 12.84 ± 0.08 Ma. The low-temperature steps of potassium feldspar
40
Ar/
39
Ar spectra yield ages of
c.
11.0–12.5 Ma and apatite fission track analyses indicate the dome uniformly cooled below
c.
115°C at 9.5 ± 0.6 Ma. Based on these data, calculated average cooling rates across the dome range from
c.
40–60°C/million years in schist and orthogneiss and following emplacement of the leucocratic dyke swarm, to
c.
350°C/million years following emplacement of the two-mica granites. The mylonitic foliation, peak metamorphic isograds, and mica
40
Ar/
39
Ar chrontours are domed, whereas the low-temperature step potassium feldspar
40
Ar/
39
Ar and apatite fission track chrontours are not, suggesting that doming occurred between 13.0 and 12.5 Ma and at temperatures between 370 and 200°C. Our new ages, along with field, structural and metamorphic data, indicate that the domal geometry observed at Mabja developed by middle-Miocene southward-directed thrust faulting upward and southward along a north-dipping ramp above cold Tethyan sediments. The structural, metamorphic and geochronologic histories documented at Mabja Dome are similar to those of Kangmar Dome, suggesting a common mode of occurrence of these events throughout southern Tibet. Vertical thinning and horizontal stretching, metamorphism, generation of migmatites, and emplacement of leucogranites in the domes of southern Tibet are synchronous with similar events in the Greater Himalayan Sequence that underlie the high Himalaya. These relations are consistent with previously proposed models for a ductile middle-crustal channel bounded above by the South Tibetan detachment system and below by the Main Central thrust in the High Himalaya that extended northward beneath southern Tibet.
Heterogeneous ductile deformation along a mid-crustal extruding shear zone: an example from the External Hellenides (Greece)
Authors: Xypolias P. , Kokkalas S.
Published: April 2008

Petrofabric, finite strain and kinematic vorticity data were used to investigate the heterogeneous nature of ductile deformation along a 1.5–2 km thick extruding shear zone in the south Peloponnese, that formed under blueschist-facies conditions. Asymmetric quartz
c
-axis fabrics confirm westward thrust movements on an east-dipping shear zone and provide evidence for localized top-down-to-the-east shear sense at the front of the zone. Strain ratio (

R
xz

) is nearly constant (
c.
3.0–4.0) along the upper structural levels of the zone but increases systematically from the middle to the bottom, approaching a value of
c.
9.5 in the frontal parts, close to the basal thrust, and a value of
c.
7.0 in the inner parts. The distribution of kinematic vorticity number depicts a simple-shear-dominated domain in the lower half of the shear zone and shows that the pure shear component always increases upwards in the zone, becoming dominant at the top of the inner parts of the zone. Integration of strain and vorticity data yields a shear-parallel elongation of
c.
60–90% at the top and
c.
40–60% at the bottom of the zone, revealing that both upper and lower surfaces of the extruding slices were ‘stretching faults’. Minimum total displacements of 25 and 41 km and slip rates of 6.5 and 10 mm/year were estimated for the basal and roof faults, respectively.
An argument for channel flow in the southern Canadian Cordillera and comparison with Himalayan tectonics
Authors: Brown Richard L. , Gibson H. Daniel
Published: April 2008

Crustal thickening in excess of 55 km, and high heat flow, suggest that a high-standing plateau region in the Cordilleran hinterland was present in the Late Cretaceous. A low strength middle crust developed beneath the plateau, and parts of this layer were exhumed to upper crustal levels in Late Cretaceous to Eocene time. During Late Cretaceous time, structures in the hinterland were reactivated. Strata, buried to mid-crustal depths since the Jurassic, began to flow upward to higher levels; earlier structures were refolded and tightened, and a new transposition fabric developed. Some 10–20 km of the middle crust was involved in high temperature ductile flow. The lower boundary of the ductile zone lies with thrust sense on top of Precambrian rocks of Canadian Shield affinity, and splays upwards to the NE where it closely coincides with highly strained rocks in the hanging wall of the Purcell Thrust Fault. The upper boundary is marked by a normal-sense high strain zone, above which only minor Cretaceous deformation occurred. The boundaries were reactivated at upper crustal levels after cessation of flow in the mid-crustal channel. This reactivation resulted in formation of ductile to brittle extension faults such as the Okanagan Fault System. During final stages of flow, the Precambrian basement gneisses at the base of the channel became domed and exhumed to upper crustal levels. Comparisons with Himalayan tectonics are clearly drawn, but there are significant contrasts such as the long residence time of the proposed Cordilleran channel, and the nature of the channel boundaries.
Ductile thrusting versus channel flow in the southeastern Canadian Cordillera: evolution of a coherent crystalline thrust sheet
Authors: Carr Sharon D. , Simony Philip S.
Published: April 2008

The Late Cretaceous Gwillim Creek shear zone (GCSZ) exposed in the core of the Valhalla complex, and located in the hinterland of the southern Canadian Rocky Mountain thrust belt, is a 5–7 km thick, easterly verging, ductile thrust zone. It was active after
c.
90 Ma and during anatexis (800°C and 800 MPa), rose eastward in the direction of transport, and its base was refrigerated from below at
c.
60 Ma by thrust translation onto a cold footwall. Extensional shear zones are younger than the GCSZ, and there is no evidence of channel flow or ductile extrusion. Instead, a 30 km thick, coherent sheet was translated on the GCSZ, which at depth was linked to the Foreland thrust belt such as to form a composite crystalline thrust sheet. Doming of the Valhalla complex may be related to Eocene thrusting beneath the complex during the last stage of shortening. A channel flow, proposed by others for the region north of the Valhalla complex, could have evolved within the crystalline sheet by activation of lateral transition zones and an upper detachment, but is no wider than 250 km, does not represent the dominant orogenic process and may represent a nascent channel.
Possibility of channel flow in the southern Canadian Cordillera: a new approach to explain existing data
Authors: Kuiper Yvette D. , Williams Paul F. , Kruse Stefan
Published: April 2008

Existing structural, metamorphic and geochronological data in and close to the Shuswap Metamorphic Complex in the southern Canadian Cordillera are shown to be consistent with a channel flow model. Four general structural levels (domains) can be distinguished in the region, based on the orientation and vergence of folds. In the lowest three levels folds are mostly recumbent, whereas in the uppermost level they are upright. The lowest three levels are interpreted as a channel flow zone. NE-verging folds of the lowest level (Domain 1, e.g. the Monashee Complex) formed during top-to-the-NE detachment flow and/or in the lower part of a channel flow zone. When detachment flow changed to channel flow, the sense of shear changed in the upper part of the channel flow zone, resulting in overprinting of NE-verging folds by SW-verging folds (Domain 2, e.g. most parts of the Shuswap Metamorphic Complex to the west of the Monashee Complex). Temperature was probably increasing, weakening a progressively larger portion of the crust, and the crustal shear zone therefore widened. Thus, in the highest structural levels within the channel flow zone, SW-verging folds developed in areas where no NE-verging folds originally formed (Domain 3, e.g. the Cariboo Mountains). The channel flow model as presented here is compatible with many of the ductile structures and accommodates existing metamorphic and geochronological data in the part of the southern Canadian Cordillera described.
Large ignimbrite eruptions and volcano-tectonic depressions in the Central Andes: a thermomechanical perspective
Authors: De Silva Shanaka , Zandt George , Trumbull Robert , Viramonte José G. , Salas Guido , Jiménez Néstor
Published: April 2008

The Neogene ignimbrite flare-up of the Altiplano Puna Volcanic Complex (APVC) of the Central Andes produced one of the best-preserved large silicic volcanic fields on Earth. At least 15 000 km
3
of magma erupted as regional-scale ignimbrites between 10 and 1 Ma, from large complex calderas that are typical volcano-tectonic depressions (VTD). Simple Valles-type calderas are absent. Integration of field, geochronological, petrological, geochemical and geophysical data from the APVC within the geodynamic context of the Central Andes suggests a scenario where elevated mantle power input, subsequent crustal melting and assimilation, and development of a crustal-scale intrusive complex lead to the development of APVC. These processes lead to thermal softening of the sub-APVC crust and eventual mechanical failure of the roofs above batholith-scale magma chambers to trigger the massive eruptions. The APVC ignimbrite flare-up and the resulting VTDs are thus the result of the time-integrated impact of intrusion on the mechanical strength of the crust, and should be considered tectonomagmatic phenomena, rather than purely volcanic features. This model requires a change in paradigm about how the largest explosive eruptions may operate.
How the development of magma chambers affects collapse calderas: insights from an overview
Authors: Aizawa K. , Acocella V. , Yoshida T.
Published: April 2008

Here we review the studies of pluton emplacement and caldera collapse, proposing a model linking the two processes. The shallow rise of magma occurs by dyking, and its emplacement occurs along major anisotropies. Many plutons are emplaced at subhorizontal discontinuities, forming sills. These will eventually grow, forming laccoliths, the most common mechanism to store shallow magma. Calderas are a surface expression of these reservoirs, and can be approximated by a piston cylinder, which sinks due to: (1) underpressure in the reservoir, producing outward-dipping reverse faults; (2) overpressure within a sill-like chamber undergoing doming; and (3) overpressure within a laccolith generating apical tensile stresses; in the latter two cases, inward-dipping normal faults form. We suggest that collapse calderas are the surface expression of pressure variations within laccoliths or tabular intrusions, Their geometric relationships depend on the shape and aspect ratio of the intrusion and its pressure conditions. Tabular intrusions, generating ring-faults mainly at their tips, form calderas with a similar width to the intrusion; laccoliths may generate ring-faults along the intrusion roof, forming calderas narrower than the intrusion. The outward or inward dip of the caldera faults results from the underpressure or overpressure conditions within the reservoir.
Ring-faults in composite volcanoes: structures, models and stress fields associated with their formation
Authors: Gudmundsson Agust , Nilsen Kristine
Published: April 2008

Most ring-faults of collapse calderas are either circular or slightly elliptical in plan view, vertical or steeply dipping, and have vertical displacements from several hundred metres to a few kilometres. Most ring-faults are dip slip. Many, however, are partly dip-slip faults and thus shear fractures, and partly ring-dykes and thus extension fractures. Ring-faults have been modelled using analytical, analogue and numerical methods. While analytical models throw light on some aspects of the conditions for ring-fault initiation, they are too general for detailed analysis of ring-fault development. By contrast, analogue and numerical models, combined with rigorous testing on field data, have in recent years provided many new ideas and improved understanding of ring-fault initiation and development. Here we present numerical models for ring-fault formation in isotropic (non-layered) and anisotropic (layered) host rocks. Magmatic underpressure (below lithostatic) or excess pressure (above lithostatic) as the only loading normally favours dyke injections rather than ring-fault formation. A spherical (circular) chamber in a volcanic field subject to (centimetre-scale) doming, tension, or both, is unlikely to trigger ring-fault formation unless the chamber is located in a very soft (low Young’s modulus) layer or has recently injected dykes. The numerical models indicate that a ring-fault (and a ring-dyke) is most likely to form, in layered as well as non-layered host rocks, in a local stress field generated by a shallow sill-like chamber in a volcanic field subject to doming, tension, or both. The diameter of the chamber must be much smaller than the diameter of the volcanic field subject to doming; in many of the numerical models the volcanic field diameter is three to five times that of the chamber diameter. For a 20-km-wide layered volcanic field, either tension or tension combined with doming may result in ring-fault formation. For a 40-km-wide layered volcanic field, tension is not necessary; doming alone is sufficient to trigger ring-fault formation.
On the mechanics of caldera resurgence of Ischia Island (southern Italy)
Authors: Carlino S. , Cubellis E. , Luongo G. , Obrizzo F.
Published: April 2008

A model of caldera resurgence was applied to the Island of Ischia to explain uplift, volcanic activity and tectonics on Mount Epomeo, as well as historical seismicity and slow ground movements recorded for the past 2000 years. A two-dimensional mechanical model was utilized for the crust, which was considered to be an elastic plate overlying a laccolith. Geometric dimensions and mechanical parameters were constrained using geological, geophysical and geochemical data.

We propose that a laccolith, with a diameter
L
of
c.
10 km, and a depth of up to 1 km in the centre of the island, triggered the caldera resurgence after the Mount Epomeo Green Tuff eruption forming the caldera (55 000 a
bp
). A bending phase and a punched laccolith phase are thought to have caused the observed deformations in the caldera. These processes control the tectonics at the boundary of the Mount Epomeo resurgent structure, volcanic activity and dynamics of the island.
Stable isotopes in aqueous sulphate as tracers of natural and contaminant sulphate sources: a reconnaissance study of the Xingwen karst aquifer, Sichuan, China
Authors: Bottrell S. H.
Published: April 2008

Isotopic compositions of sulphate (δ
18
O and δ
34
S) have been analysed in groundwaters from a karst aquifer in Xingwen, China to assess their use as indigenous tracers of different pollutant sulphate sources. Sulphate δ
18
O is highly effective at distinguishing sulphate from atmospheric ‘acid rain’ sources (higher δ
18
O values) from sulphate produced by aqueous pyrite oxidation (natural or acid mine drainage), which always has lower δ
18
O. The range of sulphate δ
34
S produced by aqueous oxidation of different pyrite sources is sufficiently wide to enable different natural and pollutant sulphate sources to be distinguished. Despite the fact that streams containing processing fines and pyrite mine drainage both derive sulphate from oxidation of ore materials, there is still a clear distinction in their sulphate δ
34
S. A combination of sulphur and oxygen isotopic measurements is thus highly effective at discriminating between all the sulphate sources to the karst aquifer and this indigenous tracer provides a powerful tool for assessing the impact of acid mine drainage on karst groundwater.
Natural and anthropogenic hazards in the karst of Jamaica
Authors: Day M. J.
Published: April 2008

About two thirds of Jamaica is karst landscape, and karstic hazards affect much of the country and about half of the population, mostly in rural areas. The karst includes extensive areas of dolines and dry valleys, together with poljes and classical tropical tower and cockpit karst. With population and urbanization increases, and as infrastructure is developed, karstic hazards are becoming more prevalent and risks are increasing. One major natural hazard is seasonal drought, which disrupts water supplies, particularly in rural areas where groundwater resources are poorly developed and residents depend on rainwater and springs. Conversely, seasonal flooding, particularly that associated with tropical storms, causes property damage and human death, injury and displacement. Ground surface subsidence and collapse threatens developing infrastructure, dwellings and livestock, but the potential for catastrophic karstic failure of industrial facilities such as dams and retention ponds, including the storage facilities associated with bauxite mining and processing, appears to be relatively limited. Slope failure also occurs, but is not often recognized as a hazard and has not been studied in detail. Human impacts include quarrying, bauxite mining, groundwater abstraction, urbanization, agricultural development and tourism. Groundwater contamination is a serious anthropogenic hazard, particularly associated with the bauxite industry. Less than 10% of the karst area is within protected areas.
Sinkhole distribution based on pre-development mapping in urbanized Pinellas County, Florida, USA
Authors: Brinkmann R. , Wilson K. , Elko N. , Seale L. D. , Florea L. , Vacher H. L.
Published: April 2008

Locating sinkholes in Pinellas County, Florida, is confounded by the presence of a cover of Quaternary sediments that mute the surface appearance of these sinkholes. As a first step in addressing the sinkhole hazard in the county, we analysed aerial photographs from 1926 and 1995 that covered the entire county. We digitized all identifiable sinkholes in each set of photographs in a GIS (Geographical Information System) using a set of criteria established to differentiate between karst depressions and depressions resulting from other geological processes. The 1926 photographs, although of low quality, helped to establish a baseline prior to urbanization. The 1995 photographs provided a post-urbanization distribution of natural sinkholes and man-made depression features (e.g. retention ponds). From these two data sets, we are able to assess natural and anthropogenic changes in the karst landscape of the study area. In particular, we discovered that 87% of the sinkhole features identified in the 1926 photographs are no longer present in the photographs from 1995. Many of the lost depressions have been incorporated into retention ponds.
Assessment of cover-collapse sinkholes in SW Sardinia (Italy)
Authors: Ardau F. , Balia R. , Bianco M. , De Waele J.
Published: April 2008

The SW part of Sardinia has been afflicted, in recent years, by several cover-collapse sinkholes mostly occurring in low-density population areas. The study area, that lies in the Iglesiente–Sulcis region, is characterized by the cropping out of the Palaeozoic basement related to the South European Hercynian chain, covered with Tertiary–Quaternary sediments. The main rock types that crop out are Palaeozoic metasandstones, metadolostones, metalimestones, shales and metaconglomerates, and Tertiary–Quaternary fluvial–lacustrine continental sediments. The combined application of several geophysical techniques, integrated with boreholes and geotechnical as well as hydrogeological measurements, proved to be very useful and promising in defining in detail the geological context in which each sinkhole has formed. Moreover, the gravity method, even when used alone, proved to be very effective in detecting the regional geological structures to which sinkholes are related.

Eventually, the historical analysis of phenomena, the geological knowledge of the Iglesiente–Sulcis area and the results of properly designed geophysical surveys allows the most probable areas for cover-collapse sinkholes to occur in the future to be determined. In fact, this research pointed out that the depth of the sediment-covered Palaeozoic bedrock is one of the major constraints in delimiting hazardous areas, leading to the construction of a preliminary hazard map. This map shows a belt of high risk, and also suggests the areas in which further geophysical and geotechnical investigations should be carried out to estimate the depth of the bedrock.
Redox Potential Measurement in Aqueous Solutions and Biological Media
Authors: Goldin Mark M. , Volkov Alexander G. , Khubutiya Mogely S. , Kolesnikov Vladimir A. , Blanchard Gary J. , Evseev Anatoly K. , Goldin Mikhail M. , Teselkin Yury O. , Davydov Boris V.
Published: April 2008

Electrochemical methods of redox potential measurements of aqueous solutions and biological media with a platinum electrode were analyzed. Probable reasons of the irreproducibility of open circuit potential measurements were considered. We suggested that accumulation of mixed oxides on the surface of platinum after each measurement may lead to potential shifts of the platinum electrode and therefore to a systematic error in redox potential measurements. Preliminary electrochemical treatment of platinum electrodes by cyclic impulses of externally applied potential was developed from the above considerations. The proposed method of measurement was tested in aqueous solutions of inorganic salts, blood, plasma and blood serum. Time dependencies of platinum electrode potential in the presence of inorganic salts and biological liquids were analyzed. We suggested defining the redox potentials of the tested solutions as potential of the platinum electrode after 10 - 30 min.
Layered Polymer Structure for pn Junction Photovoltaic Cells Prepared by Evaporative Spray Deposition using Ultradilute Solution
Authors: Maeda Ryuji , Shakutsui Masato , Tsutsui Tetsuo , Fujita Katsuhiko
Published: April 2008

We successfully fabricated polymer photovoltaic cells with bilayer structure of distinct tetrahydrofuran (THF)-soluble polymers by Evaporative Spray Deposition using Ultradilute Solution (ESDUS). The top layer of an acceptor polymer was deposited by ESDUS onto a bottom layer consisting of donor polymers (polythiophene, polyphenylenevinylene or polyfluorene). PL spectra of the bilayer cells indicated that the top layer can be formed without dissolving the bottom layer. The photovoltaic performance was improved compared with the blend cells of the donor polymer and the acceptor polymer prepared by conventional spin-coating technique. It is suggested that layered structure of a donor polymer and an acceptor polymer is more suitable for polymer photovoltaics than the blend.
Cross-talk between GlcNAcylation and phosphorylation: roles in insulin resistance and glucose toxicity
Authors: Copeland Ronald J. , Bullen John W. , Hart Gerald W.
Published: April 2008

O-linked β- N-acetylglucosamine ( O-GlcNAc) is a dynamic posttranslational modification that, analogous to phosphorylation, cycles on and off serine and/or threonine hydroxyl groups. Cycling of O-GlcNAc is regulated by the concerted actions of O-GlcNAc transferase and O-GlcNAcase. GlcNAcylation is a nutrient/stress-sensitive modification that regulates proteins involved in a wide array of biological processes, including transcription, signaling, and metabolism. GlcNAcylation is involved in the etiology of glucose toxicity and chronic hyperglycemia-induced insulin resistance, a major hallmark of type 2 diabetes. Several reports demonstrate a strong positive correlation between GlcNAcylation and the development of insulin resistance. However, recent studies suggest that inhibiting GlcNAcylation does not prevent hyperglycemia-induced insulin resistance, suggesting that other mechanisms must also be involved. To date, proteomic analyses have identified more than 600 GlcNAcylated proteins in diverse functional classes. However, O-GlcNAc sites have been mapped on only a small percentage (<15%) of these proteins, most of which were isolated from brain or spinal cord tissue and not from other metabolically relevant tissues. Mapping the sites of GlcNAcylation is not only necessary to elucidate the complex cross-talk between GlcNAcylation and phosphorylation but is also key to the design of site-specific mutational studies and necessary for the generation of site-specific antibodies, both of which will help further decipher O-GlcNAc's functional roles. Recent technical advances in O-GlcNAc site-mapping methods should now finally allow for a much-needed increase in site-specific analyses to address the functional significance of O-GlcNAc in insulin resistance and glucose toxicity as well as other major biological processes.
Human FXYD2 G41R mutation responsible for renal hypomagnesemia behaves as an inward-rectifying cation channel
Authors: Sha Qun , Pearson Wade , Burcea Lauren C. , Wigfall Darian A. , Schlesinger Paul H. , Nichols Colin G. , Mercer Robert W.
Published: April 2008

A mutation in the human FXYD2 polypeptide (Na-K-ATPase γ subunit) that changes a conserved transmembrane glycine to arginine is linked to dominant renal hypomagnesemia. Xenopus laevis oocytes injected with wild-type FXYD2 or the mutant G41R cRNAs expressed large nonselective ion currents. However, in contrast to the wild-type FXYD2 currents, inward rectifying cation currents were induced by hyperpolarization pulses in oocytes expressing the G41R mutant. Injection of EDTA into the oocyte removed inward rectification in the oocytes expressing the mutant, but did not alter the nonlinear current-voltage relationship of the wild-type FXYD2 pseudo-steady-state currents. Extracellular divalent ions, Ca2+ and Ba2+, and trivalent cations, La3+, blocked both the wild-type and mutant FXYD2 currents. Site-directed mutagenesis of G41 demonstrated that a positive charge at this site is required for the inward rectification. When the wild-type FXYD2 was expressed in Madin-Darby canine kidney cells, the cells in the presence of a large apical-to-basolateral Mg2+ gradient and at negative potentials had an increase in transepithelial current compared with cells expressing the G41R mutant or control transfected cells. Moreover, this current was inhibited by extracellular Ba2+ at the basolateral surface. These results suggest that FXYD2 can mediate basolateral extrusion of magnesium from cultured renal epithelial cells and provide new insights into the understanding of the possible physiological roles of FXYD2 wild-type and mutant proteins.
Contribution of intrarenal cells to cellular repair after acute kidney injury: subcapsular implantation technique
Authors: Curtis Lisa M. , Chen Sifeng , Chen Bo , Agarwal Anupam , Klug Christopher A. , Sanders Paul W.
Published: April 2008

The kidney is capable of regeneration following injury, particularly following acute insults. Although the mechanisms underlying cellular regeneration are incompletely understood, emerging evidence suggests a role for cells of renal origin in the repair and replacement of damaged renal tubule cells. The overall hypothesis of this study is that native kidney cells that reside in a niche in the kidney provide robust contribution to the repair of kidney tubules following injury. To test this hypothesis, we utilized a model of renal ischemia-reperfusion injury that results in extensive morphological changes, particularly in the outer medulla. Renal tissue obtained from mice constitutively expressing Escherichia coli β-galactosidase (ROSA26) was dissected from the cortex, outer medulla, or papilla and implanted under the renal capsule of the injured mice. Mice were allowed to recover for 7 days. Sections through the injured kidney demonstrated the presence of implant-derived cells in renal tubules in the outer medulla. The implanted renal region that exhibited the most robust response was the papilla, whereas tissue pieces from the cortex and outer medulla showed less contribution to recipient renal tubules. These results provide proof-of-principle evidence that renal-derived reparative cells reside in all regions of the kidney, perhaps more predominantly in the renal papilla. A greater understanding of the cell biology of renal repair by native kidney cells will provide further insight into the design of novel therapies in acute kidney injury, and the subcapsular implant technique described in this study may offer unique advantages to evaluate renal repair mechanisms.
Muscle unloading-induced metabolic remodeling is associated with acute alterations in PPARδ and UCP-3 expression
Authors: Mazzatti Dawn J. , Smith Melissa A. , Oita Radu C. , Lim Fei-Ling , White Andrew J. , Reid Michael B.
Published: April 2008

A number of physiological changes follow prolonged skeletal muscle unloading as occurs in spaceflight, bed rest, and hindlimb suspension (HLS) and also in aging. These include muscle atrophy, fiber type switching, and loss of the ability to switch between lipid and glucose usage, or metabolic inflexibility. The signaling and genomic events that precede these physiological manifestations have not been investigated in detail, particularly in regard to loss of metabolic flexibility. Here we used gene arrays to determine the effects of 24-h HLS on metabolic remodeling in mouse muscle. Acute unloading resulted in differential expression of a number of transcripts in soleus and gastrocnemius muscle, including many involved in lipid and glucose metabolism. These include the peroxisome proliferator-activated receptors (PPARs). In contrast to Ppar-α and Ppar-γ, which were downregulated by acute HLS, Ppar-δ was upregulated concomitant with increased expression of its downstream target, uncoupling protein-3 ( Ucp-3). However, differential expression of Ppar-δ was both acute and transient in nature, suggesting that regulation of PPARδ may represent an adaptive, compensatory response aimed at regulating fuel utilization and maintaining metabolic flexibility.
Improved Rational Two‐Port Model of Uniform R‐C‐NR Structure
Authors: Kumar Umesh , Jha Somesh
Published: April 2008

The indefinite admittance matrix of the uniform R‐C‐NR structure (1) is written in a modified manner. The
new expressions for the admittance parameters are expanded utilizing the technique postulated earlier by
Dutta Roy and Kumar (2). A rational two‐port lattice equivalent of the uniform R‐C‐NR structure is
constructed. This proposed model is much more accurate over a much wider frequency range and is very much
improved because it stimulates the characteristics more precisely and extensively.
Microstructural Studies of Ni‐P Thick Film Resistor Temperature Sensors
Authors: Holodnik Barbara , Jakubowicz Abram , Lukaszewicz Marian , Hauffe Wolfgang
Published: April 2008

Thick Ni‐P films have been widely investigated at our Institute. This article tends to visualize by use of various microscopic methods how the growth and sintering of individual conducting grains, results in the formation of nickel dendrites responsible for the metallic character of electrical conduction.
Control of Electrical Properties of RuO2 Thick Film Resistors
Authors: Inokuma Toshio , Taketa Yoshiaki
Published: April 2008

Oxides of various elements have been added to RuO2 thick film resistors and the electrical properties of the
resultant resistors have been examined.

It is found that almost all the oxides of transition metals, rare earths, and antimony used as additivies can
closely control the resistivity and TCR of the resistors to obtain a required value. In addition, it is found that the
principle of superposition applies to the additives.

Erratumdx.doi.org/10.1155/1987/73636
A Comparison Between GaAs Mesfet and Si NMOS ESD Behaviour
Authors: Franklin A. J. , Amerasekera E. A. , Campbell D. S.
Published: April 2008

Work is in hand at Loughborough University to investigate and compare the ESD sensitivity of GaAs
D‐MESFETs and unprotected enhancement mode NMOS structures.

The work to date has shown that GaAs MESFET structures can be severely degraded with ESD pulses above
600V as compared with 200V for Si NMOS. It has also been shown that both GaAs and NMOS structures are
polarity sensitive.

The behaviour of the Schottky barrier is used to explain the polarity behaviour in GaAs MESFETs. The
breakdown of the oxide in the NMOS devices can be explained by impact ionisation.
A 22% Efficient Semiconductor/Liquid Junction Solar Cell—the Photoelectrochemical Behavior of n‐WSe2 Electrodes in the Presence of I2/I- in Aqueous Electrolyte
Authors: Campet G. , Azaiez C. , Levy F. , Bourezc H. , Claverie J.
Published: April 2008

One of the most efficient semiconductor/liquid‐junction photoelectrochemical cells
(PEC) reported to date is presented. It consists of a SeCl4‐grown n‐WSe2 single crystal
anode, with a 3.1016 cm-3 conduction‐band electronic density, and a platinum
cathode. Both electrodes are immersed in a 2M KI + 0.005M I2 aqueous electrolyte.
The calculations of the main physical parameters determining the high value (22%) of
the visible light‐to‐electrical energy conversion efficiency have been carried out. We
particularly show that the lifetime of the photogenerated holes is larger than their
transit time across the space‐charge so that the carriers reach the semiconductor
surface, where they can react with the electrolyte, without recombining.
Dependence of the Sheet Resistivity and Current Noise Behaviour of the Grain Size and Volume Fraction of Conducting Material in Thick‐Film Resistors Experiments
Authors: Müller F. , Wolf M.
Published: April 2008

Experimental results concerning the dependence of the sheet resistivity and the noise
coefficient on the grain size and the volume fraction, respectively, of the metallic‐like
component in Bi2Ru2O7‐based thick‐film resistors are presented. The results are
compared with current models for the electrical conduction mechanism in these
resistors.
Correlation of Switching Overvoltages Over Transposed and Untransposed Transmission Lines
Authors: Hamed M. , Ismail D.
Published: April 2008

This paper presents a computational analysis of the difference between the values of the self parameters (resistance, inductance and potential coefficient) of some typical transmission lines. The earth return effect is included. A new coefficient of unsymmetry for the untransposed transmission line parameters is proposed. The wave mode parameters as a function of the given coefficient of unsymmetry are deduced.

The balancing of the parameters of both transposed and untransposed lines is applied. The percentage error in the calculated voltage at any point of the untransposed line, if considered as transposed, is formulated.
The Structure and Heat Dependence of Silicon Spreading Resistance Temperature Sensors
Authors: Pásztor Gy. , Berkecz J. , Ficza N. M.
Published: April 2008

The construction method of the sensor SRTS with two roundshaped diffusion layers is given.
The effect of geometry on the sensor resistance is determined theoretically. An approximating
method is given to determine the temperature dependence of the sensor in the range of
200K < T < 400K. Calculated results are compared to measurements.
A New Stability Test for Passivated NiCr Thin Film Resistors
Authors: Riesenberg R. , Dintner H.
Published: April 2008

A suitable short‐time test for analysis of long term stability is presented for the case of
passivated NiCr thin film resistors revealing an aging characteristic which is not of Arrhenius
type. Based on the in‐situ measurement of resistance change during a continuous temperature
rise, so‐called temperature ramp curve, a well‐defined correlation is found between the film
stability and a characteristic temperature Tp where the temperature ramp curve exhibits a
maximum. In this way, a reliable prediction of the long term stability can be made within
only a few hours. The influence of the heating rate on the characteristic temperature Tp is
shown. Furthermore, it is experimentally proved that the values of Tp are not essentially
determined by the reversible resistance changes due to differential temperature coefficient of
resistance, but indeed by irreversible aging processes.
Evaporation of Adherent Al‐Films on Single Crystalline LiNbO3 Substrates
Authors: Schippel E.
Published: April 2008

LiNbO3 is used as a single crystalline substrate material for the manufacturing of surface acoustic wave
devices as frequency selective components. On the polished substrate wafer, Al with a film thickness
of about 400 nm is evaporated in a high vacuum.

The difficulties of the inadequate adhesion of the structured Al‐film were eliminated by systematical
investigations. Films that were adherent to the total surface could be prepared by evaporating an
intermediate film of Cr or SiOx or, otherwise, a mixed film of Al with Si.

An ultrasonic test for adhesion strength was developed that results in an assessment of local and
also large‐area film adhesion.
Influence of Thermal Treatment Under Various Oxygen Pressures on The Electronic Properties of Ceramics and Single Crystals of Pure and Tin‐Doped Indium Oxide
Authors: Wen Shijie , Campet G. , Portier J.
Published: April 2008

The different electronic behaviors of pure and tin‐doped indium oxides with various thermal treatments
under high and low oxygen pressure are discussed on the basis of the evolution of the band energy
diagram. A critical concentration of “active oxygen vacancies” associated with donor centers is necessary
to achieve high electronic mobility in ITO (Indium Tin Oxide).
Humidity Effect on Chip Capacitors With Al2O3 Multistage Anodised Films
Authors: Beensh-Marchwicka G. , Król-Stepniewska L.
Published: April 2008

In this paper the properties of capacitors with porous‐barrier and barrier‐type Al2O3 layers under
humidity tests are described and compared. The capacitance, conductance and dissipation factor of
these structures were measured as a function of relative humidity ranging from 11% RH to 94% RH.
It has been found that the dependences of electrical conductance on relative humidity on a log‐log scale
are linear with the slope from 0.026 to 8.19. For capacitors with the porous‐barrier type layer the slopes
were below unity in the whole humidity range while for capacitors with the barrier‐type layer this was
only true in the low humidity range (below 60% RH). The moisture effect on capacitors with solder
bump and NiCr electrodes was extremely small. On the other hand the presence of chromium lying
direct on Al2O3 film caused a rise in humidity sensitivity. The new ingenious technique of Al2O3 dielectric
layer preparation proposed affords the possibilities of producing capacitors with very low sensitivity to
moisture in both the low‐and high‐humidity ranges.
Titanium Silicide Formation in Presence of Oxygen
Authors: Nobili C. , Nava F. , Ottaviani G. , Costato M. , De Santi G. , Queirolo G.
Published: April 2008

In‐situ resistivity vs. temperature, Rutherford backscattering spectrometry, Auger electron spectroscopy
and X‐ray diffraction measurements have been performed in order to study the effects arising from the
presence of oxygen in the annealing ambient on the integrity of amorphous films of TiSix, with x ranging
from 1.45 to 2.1. Crystalisation occurs around 400 C. The presence of oxygen produces the formation
of silicon and titanium oxide around 500 C. Critical analysis of the experimental results have indicated
that metal oxidation is inhibited when an excess of silicon is present, which suggests the use of a
sputtered Si coating cap as a medium capable of effectively decoupling the silicide film from oxygen.
This avoids unwanted Ti oxidation even in heavily oxygen contaminated ambients up to the highest
temperatures used for the formation of low resistivity titanium disilicide.
The Textural Effect of Cu Doping and the Electronic Effect of Ti, Zr and GeDopings Upon the Physical Properties of In2O3 and Sn‐Doped In2O3 Ceramics
Authors: Wen S. J. , Campet G.
Published: April 2008

The electronic properties of Cu‐, Ti‐, Zr‐, and Ge‐doped In2O3 (IO) and ITO (Sn‐doped In2O3) ceramics
are investigated. We distinguish the different effect of Cu doping (so called the “textural effect”) and
of Ti, Zr and Ge dopings (so called the “electronic effect”) of IO and ITO ceramics. Indeed, Cu doping
in IO and ITO enhances the ceramic density and thereby the conductivity due to an increase in the
carrier mobility (grain boundary effect); the absorbance in the visible region is then lowered. Most
interestingly for Ti‐, Zr‐, and Ge‐doped samples, the increase of conductivity associated with an enlargement
of the electron‐mobility along with a decrease of the absorbance in the visible, account for
the weak interactions occuring between the conduction‐band electrons and the ionized donor centers.
Relationship Among Preparation, Structure and Superconductivity inTi‐Ca‐Ba‐Cu‐O Compounds
Authors: Kirschner I. , Leppävuori S. , Uusimäki A.
Published: April 2008

Analysis of a comprehensive set of experimental results has proven the substantial effect of the precise
preparation conditions upon the structure and superconducting parameters of Ti‐Ca‐Ba‐Cu‐O samples.
The techniques required for the preparation of specimens of single phase and long‐term stability,
together with methods for improvement of the characteristic parameters have been determined. Comparing
results derived from samples prepared by different methods has allowed the quantitative differences
of the characteristic parameters to be evaluated.
X‐Ray Reflectivity Study of Reactive DC Sputter Deposited Al2O3Thin Films
Authors: Bender A. , Schippel E.
Published: April 2008

X‐ray reflection was performed on Al2O3 thin films obtained by dc magnetron sputtering of aluminium
in an argon/oxygen atmosphere. Two kind of films (amorphous and γ‐Al2O3) were deposited on polished
silicon wafers by conventional sputtering and sputtering with ion bombardment on the growing film.
The x‐ray reflection allows one to determine the surface roughness, mass density and thickness. The
thickness was compared with ellipsometry data, and mechanical scanning measurements (stylus method).
Transmission electron diffraction investigations were made for phase determination.
Some Results on PIN and ITO Photodiodes
Authors: Caffaro M. A. Grado , Caffaro M. Grado
Published: April 2008

In this paper, various contributions concerning generalized photodiodes and ITO photodiodes are
reported. In particular, calculations related to the bandwidth of the equivalent circuit ot a PIN photodiode
are performed and compared to experimental considerations. In addition, an ITO structure on
a layer n‐type GaAs is examined. An ITO‐HEMT is also considered.
Electronic and Magnetic Properties of Fe2N and FeN: Trends of the Magnetism ofthe Fe‐N System
Authors: Matar S. , Mohn P.
Published: April 2008

The electronic and magnetic properties of the nitrides Fe2N and hypothetical FeN were investigated by use of the ASW method. For both nitrides, the calculations were done in the orthorhombic structure of Fe2N for the two nitrides. The magnetization is low (0.95 μB/at.) for Fe2N and vanishes for FeN. The decrease of the magnetization with increasing amount of N is assessed within the Fe‐N system in a model derived from a Slater‐Pauling type behavior. Accordingly, a trend from weak to strong ferromagnetism is suggested.
Electronic Properties of Sn‐ or Ge‐Doped In2O3 Semiconductors
Authors: Wen S. J. , Campet G.
Published: April 2008

The thermoelectric power and Hall effect of In2O3 single crystals, either undoped or Sn doped, and of
In2O3 ceramics, either undoped or Sn or Ge doped, are investigated. All doped samples have negative
thermoelectric power values. The metal‐type conductivity occurs when the carrier concentration exceeds
l019 cm–3 The correspondence between the values of the thermoelectric power and those of the carrier
mobility and carrier concentration is given. Most interestingly this study puts into light the enhanced
carrier mobility occurring for Ge‐doped In2O3 samples compared with ITO samples (Sn‐doped In2O3
widely used in optoelectronic devices.
A Study of a‐Sic/C‐Si(n) Isotype Heterojunctions
Authors: Georgoulas N. , Magafas L. , Thanailakis A.
Published: April 2008

In the present work a study of the electrical properties of heterojunctions between rf sputtered amorphous
silicon carbide (a‐SiC) thin films and n‐type crystalline silicon (c‐Si) substrates is reported. The
current‐voltage (I‐V) and capacitance‐voltage (C‐V) characteristics, as well as the temperature dependence
of the current of a‐SiC/c‐Si(n) heterojunctions were measured. The I‐V characteristics of a‐SiC/
c‐Si(n) heterojunctions exhibit poor rectification properties, with a high reverse current, at higher
temperatures (T > 250K), whereas good rectification properties are obtained at lower temperatures (T
< 250K). It was found that the a‐SiC/c‐Si(n) heterojunctions are isotype, suggesting that‐the conductivity
of a‐SiC is n‐type. The temperature dependence of the current (from 185K to 320K) showed that the
majority carriers of c‐Si(n) (i.e. electrons) are transported from c‐Si(n) to a‐SiC mainly by the thermionic
emission mechanism, or by the drift‐diffusion mechanism. From C‐V measurements of a‐SiC/c‐Si(n)
heterojunctions the electron affinity of a‐SiC was found to be X1 = 4.20 ± 0.04 eV. Finally, the a‐SiC/
c‐Si(n) isotype heterojunctions are expected to be interesting devices as infrared
Modelling of Nonuniform RC Structures for Computer Aided Design
Authors: Abuelma′atti Muhammad Taher
Published: April 2008

A simple model for nonuniform distributed RC structures is presented. The model consists of three
passive elements only and can be used for modelling nonuniform distributed RC structures involving
exponential, hyperbolic sine squared, hyperbolic cosine squared and square taper geometries. The
model can be easily implemented for computer‐aided analysis and design of circuits and systems comprising
nonuniform distributed RC structures.
Broadband Waveguide Feed for Parabolic Reflectors
Authors: Mital P. Bhushan
Published: April 2008

The broadband requirement in microwave systems has necessitated attention on components that can
operate over frequency ranges far broader than those of standard rectangular waveguides. This paper
describes the design and development of an ridged horn to match the waveguide impedance to freespace
impedance so that the horn could be used as a feed for an offset‐fed parabolic reflector over a wide
band of frequencies, i.e., C and X bands (4.2 to 10.2 GHZ). In the present case, a five stepped chebyshev
transformer has been used. Complete design required for horn feed as well for the ridged waveguide
components necessary for testing has been carried out. The results obtained are quite encouraging.
Good agreement is found between the measured results and theoretical values.
Bends in Non‐Radiative Dielectric Guide
Authors: Mital P. Bhushan
Published: April 2008

Curved bends in NRD waveguides have been developed. Measured insertion losses of 90º and 180º
bends in an NRD guide are reported. Both the bends have insertion losses very near a reference straight
guide in the frequency range from 33.5–36.5 GHZ.