bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy Balances on a Parabolic Cylinder Solar Collector
Authors: Lof G. O. G. , Fester D. A. , Duffie J. A.
Published: January 2012

A technique for optimizing the design of focusing solar collectors was developed through a detailed study of the energy balances for a parabolic-cylindrical reflector with tubular receivers of three diameters. Experimental data for concentration ratios of 10 to 22.5 and surface temperatures of 88 to 353 deg F are presented. Receiver temperature, meteorological variables (including solar radiation), and distribution of reflected radiation in the focal zone of the reflector were measured and correlated so as to permit optimization of concentration ratio.
Radial Forces in a Pump Impeller Caused by a Volute Casing
Authors: Csanady G. T.
Published: January 2012

The volute casing of a radial flow impeller is replaced by an “equivalent” logarithmic spiral which, at the design flow rate of the pump, does not exert a force on the fluid discharged by the impeller. At other flow rates there is a nonzero angle of incidence and the spiral, which may be regarded as the single blade of a radial flow cascade, exerts a “lift” force. This force is calculated by the methods of perfect fluid theory, first mapping the spiral onto a flat-plate cascade, then establishing the pressure distribution. Incidence angle and the magnitude of the absolute exit velocity from the impeller govern the lift forces and by a consideration of the velocity triangles at impeller exit some qualitative features of the behavior of radial forces on the impeller are deduced. Quantitative comparison with the experimental results of Iversen, et al., [4] also shows good agreement.
The Effects of Nucleate Boiling Versus Film Boiling on Heat Transfer in Power Boiler Tubes
Authors: Swenson H. S. , Carver J. R. , Szoeke G.
Published: January 2012

In large, subcritical pressure, once-through power boilers heat is transferred to steam and water mixtures ranging in steam quality from zero per cent at the bottom of the furnace to 100 per cent at the top. In order to provide design information for this type of boiler, heat-transfer coefficients for forced convection film boiling were determined for water at 3000 psia flowing upward in a vertical stainless-steel tube, AISI Type 304, having an inside diameter of 0.408 inches and a heated length of 6 feet. Heat fluxes ranged between 90,000 and 180,000 Btu/hr-sq ft and were obtained by electrical resistance heating of the tube. The operation of the experimental equipment was controlled so that nucleate boiling, transition boiling, and stable film boiling occurred simultaneously in different zones of the tube. The film boiling data were correlated with a modified form of the equation Nu = a a(Re)m(Pr)n using steam properties evaluated at inside surface temperature. Results of a second series of heat-transfer tests with tubes having a helical rib on the inside surface showed that nucleate boiling could be maintained to much higher steam qualities with that type of tube than with a smooth-bore tube.
Prediction of Axial-Flow Turbomachine Performance by Blade-Element Methods
Authors: Serovy G. K. , Lysen J. C.
Published: January 2012

The blade-element method has been used effectively in the solution of the design problem for axial-flow turbomachines. A considerable body of data has been acquired to support the use of this system. The method has been applied in the investigation reported in this paper to the performance-prediction problem for blade rows in incompressible and compressible flows. Radial distributions of velocity and fluid properties were determined by numerical solution of the radial equilibrium condition, with radial entropy gradients included by using blade-element losses estimated from available experimental information. The effect of a loss gradient on the predicted performance of a typical axial-flow pump configuration is indicated and, for the case of an axial-flow compressor rotor operating in air, performance predicted is compared with experimentally measured performance.
Optimization of Focusing Solar-Collector Design
Authors: Lo¨f G. O. G. , Duffie J. A.
Published: January 2012

A set of general graphical relationships has been developed for establishing the receiver-reflector area ratio which will provide the maximum useful heat delivery from a focusing collector. The method, applied to paraboloids and parabolic cylinders, gives the optimum area ratio in terms of incident radiation intensity, optical properties (including precision of reflector), and thermal loss rate. Use of the method for design and for evaluation of existing reflectors is illustrated; its use in economic optimization will be dependent on availability of adequate cost data.
Steady-State Thermal Analysis of a Thermometer Well
Authors: Benedict R. P. , Murdock J. W.
Published: January 2012

A generalized thermometer well is analyzed as to temperature-measuring uncertainties. A reliable finite difference approximation to the differential heat balance equation is developed. For those cases where the fluid may be considered transparent to radiation (i.e., for εg ≈ 0), a simplified linearized approximation is given. Whenever conduction effects can be neglected (i.e., for (hc D/k)(L2/(D2 − d2)) > 20), a rapid hand-calculation method is indicated. Several examples of graphical approximations are given.
The Transient Response of Gas Turbine Plant Heat Exchangers—Additional Solutions for Regenerators of the Periodic-Flow and Direct-Transfer Types
Authors: London A. L. , Sampsell D. F. , McGowan J. G.
Published: January 2012

Solutions are provided in nondimensional graphical form for the transient response of the outlet fluid temperatures of a counterflow gas turbine regenerator arising from a step input change of one (either one) of the inlet fluid temperatures. Both direct-transfer and periodic-flow regenerators are considered. The periodic-flow regenerator solutions are derived as a generalized result from a limited number of computer solutions for special cases. The direct-transfer regenerator solutions are derived as a generalized result from a limited number of special case solutions obtained from an electromechanical analog. This report is a continuation and extension of previous work covered in [1, 2, 3, and 4].
Case History: Hydrogen-Damage Experience in a Boiler
Authors: Esposito D. J. , Harrington R. T.
Published: January 2012

Procedure followed and results attained in correcting boiler-water conditions causing hydrogen damage to cyclone tubes in a natural-circulation boiler at the Bridgeport Harbor Station of The United Illuminating Company.
Experiences With Hydrogen Embrittlement in the Consolidated Edison System
Authors: Dick I. B.
Published: January 2012

Boiler 40 at Astoria developed brittle failures in about 3-months operation. Feedwater was pH-adjusted and deaerating condenser and heater were in operation, but no oxygen scavenger was used. Boiler water was maintained on no-solids basis. Some condenser leakage occurred. After six months, the boiler was put on coordinated phosphate control and a pronounced hideout condition was disclosed. After about nine months of operation, brittle failures occurred in the nose tubes to the extent that replacement of the entire nose section was made. Boiler 70 at East River developed brittle failures after about 8 years of service. Feedwater pH was adjusted by cyclohexylamine. Boiler water treatment for the first 5 years was low NaOH + Na3PO4, and the last 3 years coordinated phosphate. A hideout condition also exists in this boiler. Factors of chemical control, cleaning, operation, and design are discussed. Many variables can be eliminated by comparison with other units in the system. Some factors remain unanswered. Consideration is given the fact that both boilers disclosed a considerable hideout condition when operating on coordinated phosphate treatment.
Prevention of Cyclic Thermal-Stress Cracking in Steam-Turbine Rotors
Authors: Berry W. R. , Johnsson Ivar
Published: January 2012

Recent experience with cracking of the outer surface of load-cycled, high-pressure, steam-turbine rotors is analyzed as a thermal stress-fatigue problem. Cyclic strains are evaluated as a function of the operating transient and of the detailed rotor geometry. Operating recommendations are given with the aim of reducing the incidence of such cracking.
Full-Size Pressure Vessel Testing and Its Application to Design
Authors: Kooistra L. F. , Lange E. A. , Pickett A. G.
Published: January 2012

The results of full-size pressure vessel tests are summarized and used to demonstrate the validity of design procedures developed by others. In particular, design for low cycle (plastic) fatigue strength and fracture safety are investigated. The results justify the design stress recommendations made by PVRC to ASME and confirm the NRL fracture analysis diagram procedure hypothesis. It is emphasized that full advantage can be taken of high strength materials only by improvement of fabrication and inspection procedures.
Fracture Toughness and Pressure Vessel Performance
Authors: Carman C. M. , Armiento D. F. , Markus H.
Published: January 2012

Criteria for predicting pressure vessel performance based on fracture toughness are reviewed in general terms. Experimental studies of small pressure vessels fabricated of high toughness, high strength steel 4330V (Mod + Si) are described. Data presented include fatigue life in presence of a small part-through-crack and burst properties of the fatigue cracked cylinders. Interpretation of the fatigue data is based on Paris’ relationship dadN=K4M. The failure stresses are discussed in relation to the stress elevating effect of local bulging on the apparent fracture toughness. The behavior observed in testing full scale high strength pressure vessels fabricated from materials having intermediate fracture toughness, namely, D6A steel at 200,000-psi yield strength and 300M steel at 230,000-psi yield strength and materials having limited fracture toughness, namely, twenty percent nickel maraging steel at 280,000-psi yield strength, are discussed in relation to the ratio of fracture toughness to plane-strain fracture toughness based on the part-through-crack model. Precautions necessary for fabrication and inspection to insure reliable performance are discussed.
A Progress Report—Fundamentals of Thermochemical Corrosion Reactions
Authors: Levy Arthur , Merryman E. L.
Published: January 2012

This paper describes original work on the reactions of sulfur with oxygen in flame systems of H2S-O2-Ar, where the stabilized thin flame was microprobed and the quenched products of reaction were examined with a mass spectrometer. Problems in identifying reaction products are described. Although the mass spectrometer was shown capable of checking wet analyses for mixtures of gases, the composition of combustion products was not determinable accurately by this method. Preliminary kinetic data are presented for both, homogeneously and heterogeneously (catalytically) produced SO2 and SO3.
Fuels for Advanced Power Generation Systems
Authors: Way S. , Young W. E. , Tuba I. S. , Chambers R. L.
Published: January 2012

This paper discusses the relative merits of various fuels for magnetohydrodynamic power systems in which the MHD generator operates on combustion products and is coupled with a steam plant or gas turbine. The method of calculating the equilibrium gas composition is first discussed, and results are then given for alkali seeded product gas compositions and properties for cases of bituminous coal, coke, natural gas, residual oil, and alcohol. Electrical conductivity, electron mobility, and attainable flame temperatures are evaluated. Fuels of low hydrogen content are shown to be advantageous, and it is shown to be desirable to introduce the alkali seed in a dry state.
Elimination of Destructive, Self-Excited Vibrations in Large, Gas and Oil-Fired Utility Units
Authors: Cohan L. J. , Deane W. J.
Published: January 2012

As oil and gas-fired steam generators have grown in size, instances of self-excited vibrations have increased. This paper deals with the steps taken by one manufacturer to study the source of these vibrations and then eliminate them through prebaffling of sensitive gas passes. The method of determining baffle spacings for various gas-pass widths is detailed, together with the necessary mathematical background.
Instability of a Hydraulic Turbine With a Very Long Penstock
Authors: Ruud F. O.
Published: January 2012

Hydraulic turbine instability at speed-no-load was experienced during the initial operation of two impulse turbines having very long penstocks. This paper describes the steps taken to achieve stability, including alteration of the mechanism between the governor and the needle servomotors. It is shown that while different governor dashpot settings may affect the operation of the governing mechanism, other changes in the mechanism external to the governor also profoundly affect the operation of the unit.
The Effects of Fluid Properties on Cavitation in Centrifugal Pumps
Authors: Spraker W. A.
Published: January 2012

An analytical model of the cavitation process in a pump is developed assuming that the flow is adiabatic, frictionless, steady, and irrotational. A relationship is developed relating the volume percentage of the fluid vaporized during the cavitation process to the “thermal cavitation parameter.” Two assumptions are then introduced concerning the cavitation process in a pump pumping fluids of different cavitation characteristics. Using these assumptions, a relationship is derived indicating that the difference in net positive suction head (NPSH) of a given pump handling two fluids is a function of the difference of the reciprocals of the thermal cavitation parameter for the two fluids and of the volume percentage of the fluid vaporized. This relationship is compared with data describing the cavitation characteristics of six pumps handling four pure fluids. The change in NPSH for all of the pumps and fluids, using the cold-water NPSH as a reference, is found to correlate as a function of the reciprocal of the thermal cavitation parameter with an accuracy of ±1 ft in NPSH. Experimental and analytical methods for determining the cavitation characteristics of pumps handling petroleum-based hydrocarbon mixtures are then described. Cavitation data for two pumps handling gasoline, fuel oil, and crude oil are presented. The data correlation for pure fluids is extended to include cavitation data for petroleum-based hydrocarbon mixtures. It is found that mixtures exhibit an additional decrement in NPSH over that for pure fluids having the same value of the thermal cavitation parameter. This additional decrement is found to be temperature dependent.
An Investigation Into Unsteady Blade Forces in Turbomachines
Authors: Lefcort M. D.
Published: January 2012

The wake interaction problem in a turbomachine has been simulated in a water table. The pressure distribution over a compressor blade during a passage of a wake shed by an upstream wake generator has been determined experimentally using specially developed piezoelectric pressure transducers. The thin airfoil-wake theory has been extended to cover the case of wakes of finite thickness. An attempt has been made to predict the pressure perturbation induced at the blade prior to the arrival of the wake due to the potential flow about an upstream blade. The effect of the distortion of the wake while on the blade is demonstrated; the difference between the computed and measured pressure perturbations indicates the need for taking account of this effect.
SO3 Formation in H2S Flames
Authors: Levy A. , Merryman E. L.
Published: January 2012

The microstructure of H2S-O2 flames has been developed in terms of composition and temperature profiles. With the aid of these profiles, rates of formation of SO2 and SO3 are reported and discussed. With the aid of kinetics and thermodynamic data developed for the principal reaction steps, it is shown that a major part of the SO3-problem may be related to the O-atom oxidation of SO2 in the flame. These fundamental studies of thermochemical reactions provide the basic information needed as the next step in understanding how reactions in flames and on surfaces affect external corrosion and deposits in boiler furnaces.
Basic Analysis of Pressure-Control Systems Used on Large Steam Turbine-Generator Units
Authors: Callan P. C. , Eggenberger M. A.
Published: January 2012

A method is described for the analysis of pressure-control systems used on large steam turbine-generator units which permits the evaluation of the performance of the system with respect to stability and response with a minimum of detailed knowledge of the system. Commonly occurring nonlinear elements are included in the analysis.
Flow Losses in Abrupt Enlargements and Contractions
Authors: Benedict R. P. , Carlucci N. A. , Swetz S. D.
Published: January 2012

In this paper, we examine losses associated with compressible and constant-density fluids flowing across abrupt area changes in flow passages. The bases of the conventional constant-density loss coefficients for abrupt enlargements and contractions are first reviewed. A loss parameter based directly on the drop in total pressure is next introduced. Various compressible-flow solutions are then considered. Results are given of new experiments run with air and water flowing across abrupt area changes. The total-pressure-loss parameter is shown to have greater utility and validity than the usual loss coefficient for both compressible and constant-density flows.
Traveling-Wave Vibration of Gas-Turbine Engine Shells
Authors: Macke H. J.
Published: January 2012

Two related analyses are presented to account for the presence of traveling-wave vibration in stationary and rotating cylindrical shells in gas-turbine engines. Governing equations are developed and shown to correlate well with experimentally determined evidence. For stator casings enclosing rotating blades, a criterion for minimum wall thickness is developed. For rotor shells, relations for forward and backward-traveling waves are compared with the corresponding well-known relations for disks.
Use of Arbitrary Quasi-Orthogonals for Calculating Flow Distribution in a Turbomachine
Authors: Katsanis Theodore
Published: January 2012

A method of analyzing flow through a turbomachine which is suitable for computer programming is summarized. The method, which has been reported in NASA publications, is based on an equation for the velocity gradient along an arbitrary quasi-orthogonal rather than the normal to the streamline as used in previous methods. A quasi-orthogonal is defined to be any curve that intersects every streamline between the flow boundaries exactly once, as does an orthogonal to the streamlines. With this method a streamline analysis can be made on any given stream surface. A quasi-three-dimensional solution can be obtained by using the method for a hub-to-shroud analysis, followed by blade-to-blade analyses at hub, mean, and shroud. As an example, the method was applied to the radial-inflow turbine with splitter blades. The complete quasi-three-dimensional solution was obtained in a single computer run.
Life Sciences at a Crossroads: Respiratory Transmissible H5N1
Authors: Osterholm Michael T. , Henderson Donald A.
Published: January 2012

Release of details of recent research on affecting influenza transmissibility poses far more risk than any good that might occur.
The Limits of Government Regulation of Science
Authors: Kraemer John D. , Gostin Lawrence O.
Published: January 2012

A transparent institutional review process will balance scientific freedom and national security better than publication restrictions.
Two outbreaks of neuropathogenic equine herpesvirus type 1 with breed‐dependent clinical signs
Authors: Barbić L. , Lojkić I. , Stevanović V. , Bedeković T. , Starešina V. , Lemo N. , Lojkić M. , Madić J.
Published: January 2012

Equine herpesvirus type 1 (EHV‐1) is a worldwide spread pathogen of horses. It can cause abortion, respiratory and neurological disease and consequentially significant economic losses in equine industries. During 2009, two outbreaks of EHV‐1 were confirmed in two stud farms in Eastern Croatia. The first outbreak occurred in February following the import of 12 horses from USA, serologically negative to EHV‐1 before transport. Four mares aborted in the late stage of pregnancy and one perinatal death was recorded. Other six mares showed clinical signs of myeloencephalopathy with fatal end in four. One month later, the second EHV‐1 outbreak was confirmed in stud farm about 100 km further with 17 abortions, three perinatal deaths and one mild neurological case. Epidemiological data showed that the disease was probably introduced in the first stud farm during international transport. The second outbreak started with the introduction of clinically healthy stallion from the first stud farm. Molecular characterisation and phylogenetic analysis confirmed that, despite different clinical signs, the identical virus caused both outbreaks. Both horse populations were free from EHV‐1 infection before the outbreak and had not been vaccinated. Significant difference in clinical signs could be explained by different breed‐related risk factors.
PRODUCT OF REAL SPECTRAL TRIPLES
Authors: DĄBROWSKI LUDWIK , DOSSENA GIACOMO
Published: January 2012

We construct the product of real spectral triples of arbitrary finite dimension (and arbitrary parity) taking into account the fact that in the even case there are two possible real structures, in the odd case there are two inequivalent representations of the gamma matrices (Clifford algebra), and in the even-even case there are two natural candidates for the Dirac operator of the product triple.
GREENHOUSE GAS EMISSIONS OF A DISTRICT COOLING SYSTEM UTILIZING WASTE HEAT FROM A COGENERATION PLANT
Authors: KANG BYUNG HA , YUN CHANG HO , KIM SUKHYUN
Published: January 2012

Reduction effect of greenhouse gas emissions from district cooling system by using waste heat from a cogeneration plant has received specific attention from the perspective of national energy and environmental policy, and was studied in this work. For each cooling system of a residential and commercial building, greenhouse gas emissions was estimated and compared to quantify reduction effect on emissions where the heat source of heat-powered cooling system was replaced with a cogeneration waste heat. In addition, to address the problem that the values of waste heat and CEF vary depending on variables such as national or geographical conditions, a general-purpose criterion to measure the utility of substituting a district cooling for a conventional system was suggested.
The Cretaceous–Palaeogene boundary at Stevns Klint, Denmark: inversion tectonics or sea-floor topography?
Authors: Lykke-Andersen Holger , Surlyk Finn
Published: January 2012

The Cretaceous–Palaeogene boundary interval is exposed over 12 km in the coastal cliff, Stevns Klint, Denmark. An important lowermost Danian hardground has been interpreted as an originally horizontal marine abrasion surface. Its present elevation varies, from a few metres below, to about 35 m above sea level. This relief has traditionally been considered as resulting from late or post-Danian Laramide folding. New seismic profiles offshore Stevns Klint show, however, that the Base-Chalk reflector is not folded, is remarkably planar and has a gentle northward dip. Thus, the folding hypothesis cannot be upheld. Seismic stratigraphic analysis of the Chalk Group necessitates a fundamental revision of general ideas of chalk deposition. A highly irregular sea-floor topography was formed at many levels, and includes broad valleys, ridges, channels, drifts and mounds. A system of major WNW–ESE-oriented valleys and ridges can be traced into the succession exposed in Stevns Klint and further inland where it corresponds to the relief of the Cretaceous–Palaeogene boundary. The marked topographic elements of the chalk sea floor are elongate, with a WNW orientation roughly parallel to the axis of the Danish Basin and to the Sorgenfrei–Tornquist Zone forming the NE border of the basin. The sea-floor relief undoubtedly reflects the influence of strong contour-parallel bottom currents. The Cretaceous–Palaeogene boundary succession at Stevns Klint was thus developed on an underlying sea-floor topographic relief of about 40 m. Recognition of the highly irregular, current-influenced topography of the late Cretaceous sea floor stands in marked contrast to the conventional picture of quiet pelagic deposition of the chalk.
Testing models of Late Palaeozoic–Early Mesozoic orogeny in Western Turkey: support for an evolving open-Tethys model
Authors: Robertson Alastair H. F. , Ustaömer Timur , Pickett Elizabeth A. , Collins Alan S. , Andrew Theo , Dixon John E.
Published: January 2012

Field evidence from north–south transects tests three tectonic models for Tethys in Western Turkey for when a Late Palaeozoic ocean was closing and an Early Mesozoic ocean opening. In Model 1, a Palaeozoic ocean subducted southwards, rifting continental fragments from Gondwana and opening a Triassic Neo-Tethys to the south. Closure and collision occurred by latest Triassic time. In Model 2, a wide Palaeozoic Tethys subducted northwards with an active Eurasian margin and a passive Gondwana margin. The northern Gondwana margin rifted in the Triassic; fragments either remained nearby (Taurides) or drifted northwards (e.g. Karakaya) attached to a north-subducting plate. New oceanic crust replaced Palaeo-Tethys with Neotethys and back-arc marginal basins opened along the south Eurasian margin (e.g. Küre). In Model 3, a Palaeozoic ocean also subducted northwards opening wide marginal basins. A wide Southern Neotethys opened along the Gondwana margin. Rifted Eurasian (Anatolides) and Gondwana (Taurides) fragments collided in mid-Tethys by latest Triassic time. Field evidence from the Pontides supports north-dipping subduction models (Model 2 or 3 above). Key features are a south-vergent, HP–LT accretionary prism, magmatic arc and back-arc basin system bordering the Eurasian margin. Also, evidence from the Tauride Mountains favours Model 2 over Model 3. Critically, the Anatolides and Taurides appear to have a common history and were unlikely to have been located on opposite sides of Tethys, as in Model 3.
Bainang Terrane, Yarlung–Tsangpo suture, southern Tibet (Xizang, China): a record of intra-Neotethyan subduction–accretion processes preserved on the roof of the world
Authors: Ziabrev Sergey V. , Aitchison Jonathan C. , Abrajevitch Alexandra V. , Badengzhu  , Davis Aileen M. , Luo Hui
Published: January 2012

The Bainang terrane, an intra-oceanic island arc subduction complex into which Tethyan oceanic rocks were accreted during the Cretaceous, is preserved within the Yarlung–Tsangpo suture zone of Tibet. The lithostratigraphic succession established from field mapping records a long history of sedimentation in different portions of the central Tethyan domain from Late Triassic to mid-Cretaceous time. These rocks are preserved within a south-verging imbricate thrust stack of thin (≪1 km thick) northward younging tectonic slices. Five lithotectonic units were mapped in the terrane and these units are assigned to two distinct tracts. The northern tract, which accumulated on the north side of Neotethys, was probably separated from its southern counterpart by a mid-ocean ridge. Detailed radiolarian biostratigraphy is used to constrain the timing of depositional events within each tract. Oceanic plate stratigraphy of the northern tract records its northward travel and mid-Cretaceous (late Aptian) approach towards a south-facing intra-oceanic subduction zone. Rocks in the southern tract developed closer to the Indian subcontinent and experienced thermotectonic subsidence and Mid-Jurassic basic alkaline intraplate magmatism. They were probably accreted late in the Cretaceous. Variations in structural style across the terrane indicate deformation at different depths and vertical growth of the wedge rather than lateral accretion. The overall tectonostratigraphy of the terrane reflects its development in a remote intra-oceanic setting.
A palaeomagnetic and palaeobiogeographical perspective on latest Neoproterozoic and early Cambrian tectonic events
Authors: Meert J.G. , Lieberman B.S.
Published: January 2012

During the latest Neoproterozoic to Mid-Cambrian time (580–505 Ma ago), the Earth underwent significant changes in palaeogeography that included rifting of a possible supercontinent and the near simultaneous formation of a second, slightly smaller supercontinent. It is against this tectonic backdrop that the Cambrian radiation occurred. Although the general tectonic setting during this interval is fairly well constrained, models of the exact palaeogeography are controversial because of the lack of reliable palaeomagnetic data from some of the continental blocks. Palaeogeographical models based on palaeomagnetic data range from a high-latitude configuration for most continents, to a low-latitude configuration for most continents, or to rapid oscillations in continental configurations triggered by inertial changes within the planet. Palaeobiogeographical data can also be used to help constrain palaeogeographical models. To this end we use vicariance patterns in olenellid trilobites to determine their compatibility with three end-member palaeogeographical models derived from palaeomagnetic data for the Neoproterozoic and early Cambrian. The most congruent palaeogeographical model with respect to the palaeobiogeographical data described herein is the high-latitude configuration for most continents. Those palaeomagnetic models that predict inertial interchange true polar wander or multiple episodes of true polar wander differ significantly from the results from palaeobiogeography. The low-latitude palaeogeographical models also differ from the results from palaeobiogeography, but this may partly arise because of a lack of palaeomagnetic and palaeobiogeographical data from many parts of present-day South America and Africa.
40
Ar/
39
Ar age constraints on ore deposition and cooling of the Bushveld Complex, South Africa
Authors: Nomade Sebastien , Renne Paul R. , Merkle Roland K.W.
Published: January 2012

The UG-2 chromitite layer in the upper critical zone of the Rustenburg Layered Suite is one of the prominent platinum-group element enrichment zones of the
c
. 2.06 Ga Bushveld Complex (South Africa). Eleven biotite crystals were selected from a production concentrate from the Impala Platinum mine and degassed incrementally with a CO
2
laser. The apparent age spectra display widely varying characteristics, ranging from essentially 100% concordant to strongly discordant (in some cases undulatory) as a result of various degrees of chloritization of the grains. The least discordant spectra (seven grains, 90–100%
39
Ar released) yield integrated and plateau ages ranging from 2037 to 2049 Ma (relative to the Fish Canyon sanidine standard at 28.02 Ma) and share a weighted mean age of 2042.4 ± 3.2 Ma (2σ, excluding systematic errors). This age is slightly younger than existing constraints from U–Pb dating (
c
. 2055–2061 Ma), which seem to indicate a cooling rate of around 20 °C/Ma. However, the recently inferred
c
. 1% bias between currently used calibrations of the
40
Ar/
39
Ar and U–Pb systems implies a very rapid cooling rate for the Bushveld Complex between 700 and <500 °C. The possibility of subtle bias as a result of recoil artefacts must be considered. In all cases, the heterogeneous age spectra yielded older apparent plateau ages, revealing the likelihood for erroneous conclusions to be drawn from less complete data sets.
Immunotype and Immunohistologic Characteristics of Tumor-Infiltrating Immune Cells Are Associated with Clinical Outcome in Metastatic Melanoma
Authors: Erdag Gulsun , Schaefer Jochen T. , Smolkin Mark E. , Deacon Donna H. , Shea Sofia M. , Dengel Lynn T. , Patterson James W. , Slingluff Craig L.
Published: January 2012

Immune cells infiltrating the microenvironment of melanoma metastases may either limit or promote tumor progression, but the characteristics that distinguish these effects are obscure. In this study, we systematically evaluated the composition and organization of immune cells that infiltrated melanoma metastases in human patients. Three histologic patterns of immune cell infiltration were identified, designated immunotypes A, B, and C. Immunotype A was characterized by no immune cell infiltrate. Immunotype B was characterized by infiltration of immune cells limited only to regions proximal to intratumoral blood vessels. Immunotype C was characterized by a diffuse immune cell infiltrate throughout a metastatic tumor. These immunotypes represented 29%, 63%, and 8% of metastases with estimated median survival periods of 15, 23, and 130 months, respectively. Notably, from immunotypes A to C, there were increasing proportions of B cells and decreasing proportions of macrophages. Overall, the predominant immune cells were T cells (53%), B cell lineage cells (33%), and macrophages (13%), with natural killer and mature dendritic cells only rarely present. Whereas higher densities of CD8+ T cells correlated best with survival, a higher density of CD45+ leukocytes, T cells, and B cells also correlated with increased survival. Together, our findings reveal striking differences in the immune infiltrate in melanoma metastases in patients, suggesting microenvironmental differences in immune homing receptors and ligands that affect immune cell recruitment. These findings are important, not only by revealing how the immune microenvironment can affect outcomes but also because they reveal characteristics that may help improve individualized therapy for patients with metastatic melanoma. Cancer Res; 72(5); 1070–80. ©2012 AACR.
HDL of Patients with Type 2 Diabetes Mellitus Elevates the Capability of Promoting Breast Cancer Metastasis
Authors: Pan Bing , Ren Hui , He Yubin , Lv Xiaofeng , Ma Yijing , Li Jing , Huang Li , Yu Baoqi , Kong Jian , Niu Chenguang , Zhang Youyi , Sun Wen-bing , Zheng Lemin
Published: January 2012

Purpose: Epidemiologic studies suggested complicated associations between type 2 diabetes mellitus and breast cancer. High-density lipoprotein (HDL) is inversely associated with the risk and mortality of breast cancer. Our study is to determine the different effects of normal and diabetic HDL on breast cancer cell metastasis.

Experimental Design: MDA-MB-231 and MCF7 cells were treated with N-HDL, D-HDL, G-HDL, and Ox-HDL. Cell metastasis potency was examined using a tail-vein injection model, and cell adhesion abilities to human umbilical vein endothelial cells (HUVEC) and extracellular matrix (ECM) were determined in vitro. Integrin expression and protein kinase C (PKC) activity were evaluated, and PKC inhibitor was applied.

Results: D-HDL dramatically promoted cell pulmonary metastasis (103.6% increase at P < 0.001 for MDA-MB-231 with 1 × 105 cell injection; 157.1% increase at P < 0.05 for MCF7 with 4 × 105 cell injection) and hepatic metastasis (18.1-fold increase at P < 0.001 for MCF7 with 4 × 105 cell injection), and stimulated higher TC-HUVECs adhesion (21.9% increase at P < 0.001 for MDA-MB-231; 23.6% increase at P < 0.05 for MCF7) and TC-ECM attachment (59.9% and 47.9% increase, respectively, for MDA-MB-231 and MCF7, both at P < 0.01) compared with N-HDL. D-HDL stimulated higher integrin (β1, β2, β3, and αν) expression on cell surface and induced higher PKC activity. Increased TC-HUVECs and TC-ECM adhesion induced by D-HDL, G-HDL, and Ox-HDL could be inhibited by staurosporine.

Conclusions: Our study showed that glycation and oxidation of HDL in diabetic patients could lead to abnormal actions on breast cancer cell adhesion to HUVECs and ECM, thereby promoting metastasis progression of breast cancer. This will largely draw the attention of HDL-based treatments in the diabetes patients with breast cancer. Clin Cancer Res; 18(5); 1246–56. ©2012 AACR.
HIV Types, Groups, Subtypes and Recombinant Forms: Errors in Replication, Selection Pressure and Quasispecies
Authors: Eberle Josef , Gürtler Lutz
Published: January 2012

HIV-1 is a chimpanzee virus which was transmitted to humans by several zoonotic events resulting in infection with HIV-1 groups M–P, and in parallel transmission events from sooty mangabey monkey viruses leading to infections with HIV-2 groups A–H. Both viruses have circulated in the human population for about 80 years. In the infected patient, HIV mutates, and by elimination of some of the viruses by the action of the immune system individual quasispecies are formed. Along with the selection of the fittest viruses, mutation and recombination after superinfection with HIV from different groups or subtypes have resulted in the diversity of their patterns of geographic distribution. Despite the high variability observed, some essential parts of the HIV genome are highly conserved. Viral diversity is further facilitated in some parts of the HIV genome by drug selection pressure and may also be enhanced by different genetic factors, including HLA in patients from different regions of the world. Viral and human genetic factors influence pathogenesis. Viral genetic factors are proteins such as Tat, Vif and Rev. Human genetic factors associated with a better clinical outcome are proteins such as APOBEC, langerin, tetherin and chemokine receptor 5 (CCR5) and HLA B27, B57, DRB1*1303, KIR and PARD3B.
Targets for Inhibition of HIV Replication: Entry, Enzyme Action, Release and Maturation
Authors: Sierra Saleta , Walter Hauke
Published: January 2012

Inhibition of HIV replication initially targeted viral enzymes, which are exclusively expressed by the virus and not present in the human cell. The development of reverse transcriptase (RT) inhibitors started with the discovery of antiretroviral activity of the nucleoside analog zidovudine in March 1987. Currently, six major classes of antiretroviral drugs are used for the treatment of HIV-infected patients: the RT inhibitors, nucleoside inhibitors and nonnucleoside inhibitors, the protease inhibitors, the integrase inhibitor raltegravir, the fusion inhibitor enfuvirtide (T-20), and the chemokine receptor 5 antagonist maraviroc. A seventh class, the maturation inhibitors, has not yet been approved as their effectiveness is impaired by HIV-1 polymorphisms naturally occurring in 30–40% of HIV-1 therapy-naive isolates. The use of antiretroviral combination therapy has proven to be effective in delaying progression to AIDS and to reconstitute the immune system of HIV-infected individuals. During the last 5 years, the introduction of the newest antiretrovirals has increased treatment efficacy tremendously. However, the development and accumulation of resistance to all antiretroviral drug classes are still a major problem. Additional targets will have to be defined to achieve the ultimate goal: the eradication of the virus from the infected human body.
Epidemiology of Transmitted Drug Resistance in Chronically HIV-Infected Patients in Germany: The RESINA Study 2001–2009
Authors: Oette Mark , Reuter Stefan , Kaiser Rolf , Lengauer Thomas , Fätkenheuer Gerd , Knechten Heribert , Hower Martin , Pfister Herbert , Häussinger Dieter ,   RESINA Study group
Published: January 2012

Objectives: Transmitted HIV drug resistance may impair treatment efficacy of combination antiretroviral therapy (ART). This study describes the epidemiology of transmitted resistance in chronically infected patients. Methods: In a prospective multicenter trial in Nordrhein-Westfalen, Germany, transmitted drug resistance was determined by genotypic resistance testing in patients on initiation of first-line ART. Results: From 2001 to 2009, 2,078 patients were enrolled in the study. 79.9% were male, 81.2% were Caucasians, and a homosexual transmission mode was found in 51.3%. Of these patients, 41.5% were at the stage of AIDS, median CD4 cell count was 230/µl, and median viral load was 64.466 copies/ml. Transmitted drug resistance mutations were seen in 9.2% (95% CI, 7.9–10.4). Resistance in the nucleoside reverse transcriptase inhibitor class was found in 5.8% (4.8–6.8), in the nonnucleoside reverse transcriptase inhibitor class in 2.8% (2.1–3.6), and in the protease inhibitor class in 2.7% (2.0–3.4). After a continuous increase to a level above 10% in the years 2006 and 2007, a decline of drug resistance prevalence followed in 2008 and 2009. Conclusions: Transmitted HIV drug resistance was found in around 10% of chronically infected patients in Germany who started their ART. We showed a moderate decline of the prevalence of mutant virus strains in recent years. Further surveillance of this phenomenon is mandatory.
Responses to Switching to Maraviroc-Based Antiretroviral Therapy in Treated Patients with Suppressed Plasma HIV-1-RNA Load
Authors: Vitiello Paola , Brudney Daniel , MacCartney Malcolm , Garcia Ana , Smith Colette , Marshall Neal , Johnson Margaret , Geretti Anna Maria
Published: January 2012

Background: Maraviroc (MVC) has shown good efficacy and tolerability in treatment-naive and treatment-experienced HIV-1-infected patients with CCR5-tropic virus. Data on patients switching to MVC while on suppressive antiretroviral therapy (ART) are limited. The aim of this study was to evaluate patients on suppressive ART switching to an MVC-containing regimen (MVC-CR), and test the hypothesis that the switch may have an impact on T cell activation. Methods: The study population comprised 20 treated adults who started MVC with a plasma HIV-1-RNA load (viral load, VL) of <50 copies/ml. Viral tropism was assessed by V3 loop sequencing using proviral DNA from peripheral blood mononuclear cells (PBMCs). Changes in clinical and laboratory parameters were evaluated at a median of 2 and 6 months of follow-up. T cell activation was determined by measuring soluble CD30 in plasma. Results: Reasons for switching to a MVC-CR were drug toxicity and tolerability, low CD4 cell count and ART simplification. Over median 7.5 months of follow-up, 3/20 patients discontinued MVC due to severe headache, fatigue and VL rebound. A significant reduction in soluble CD30 levels in MVC-treated patients was observed during follow-up at both 2 (p = 0.027) and 6 months (p = 0.001). Conclusions: Switching suppressive ART to a MVC-CR based upon genotypic tropism prediction from proviral DNA improves tolerability. The observed impact on T cell activation warrants further investigation.
Renal Replacement Therapy in Geriatric End-Stage Renal Disease Patients: A Clinical Approach
Authors: Kooman Jeroen P. , Cornelis Tom , van der Sande Frank M. , Leunissen Karel M.L.
Published: January 2012

The number of geriatric patients on dialysis is increasing. This is due to demographic factors, a wider acceptance of elderly patients on dialysis, and an earlier start of dialysis in this patient group. Recent studies have questioned the effect of dialysis on quality of life in elderly patients with severe comorbidity and showed limited survival in this specific patient group. Therefore, the decision whether or not to start dialysis may be a difficult one for both the clinician and patient. Risk scores can be of help in facilitating shared decision making, but not as a tool to withhold dialysis. However, in the elderly patient with severe comorbidity, conservative care can sometimes be a reasonable alternative to dialysis. In the process of shared decision making, a balance should be pursued between life expectancy and quality of life. If the decision to initiate dialysis is taken, choices have to be made regarding dialysis modality and treatment prescription. If adequate support is provided, assisted peritoneal dialysis can be an acceptable alternative to hemodialysis. Care for the elderly with end-stage renal disease should be undertaken by a multidisciplinary team with special dedication to a multidimensional approach in this population.
Should Women Receive Left Ventricular Assist Device Support?
Authors: Hsich Eileen M. , Naftel David C. , Myers Susan L. , Gorodeski Eiran Z. , Grady Kathleen L. , Schmuhl Darlene , Ulisney Karen L. , Young James B.
Published: January 2012

Background—

Small studies have reported women to have worse outcomes and more adverse events after implantation of mechanical circulatory support device compared with men. To further evaluate sex differences in outcome, we used the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS).

Methods and Results—

There were 401 women (pulsatile devices=78) and 1535 men (pulsatile devices=402) from 89 institutions who were prospectively enrolled into the INTERMACS database for primary implantation of a left ventricular assist device (LVAD) between June 23, 2006, and March 31, 2010. Extensive preimplantation and outcome data were collected on all patients. With a mean follow-up of 7 months, 67 females (17%) died and 250 males (16%) died. There was no statistically significant sex difference in mortality for either pulsatile-flow (
P
=0.82) or continuous-flow (
P
=0.95) devices in adjusted and unadjusted models. There were also no statistically significant sex differences with time to first infection, bleeding, or device malfunction. However, female sex was associated with an increased hazard of first neurological event (adjusted hazard ratio, 1.44; 95% CI, 1.05–1.96;
P
=0.020).

Conclusions—

There were no significant sex differences in mortality, time to first infection, bleeding, or device malfunction with either pulsatile- or continuous-flow LVADs. However, women had an increased risk of first neurological event. For urgent/emergent mechanical support, the benefit of LVAD support likely outweighs the risk, but it remains less clear for women undergoing elective LVAD implantation.
Buoyancy Arrest and Shelf–Ocean Exchange
Authors: Brink K. H.
Published: January 2012

When steady flow in a stratified ocean passes between the continental slope and open ocean, its ability to cross isobaths is potentially limited by buoyancy arrest. If the bottom Ekman transport vanishes and there are no interior stresses, then steady linear flow on an f plane must be geostrophic and follow isobaths exactly. The influence of arrest on cross-shelf transport is investigated here to establish 1) whether there are substantial penetration asymmetries between cases with upwelling and downwelling in the bottom boundary layer; 2) over what spatial scales, hence in what parameter regime, buoyancy arrest is important; and 3) the effects of depth-dependent interior flow. The problem is approached using scalings and idealized numerical models. The results show that there is little or no asymmetry introduced by bottom boundary layer behavior. Further, if the stratification is weak or moderate, as measured by a slope Burger number s = αN/f (where α is the bottom slope, N is buoyancy frequency, and f is the Coriolis parameter), buoyancy arrest does not exert a strong constraint on cross-isobath exchange.
Pragmatism and interest: Immobilism of social work in the welfare state
Authors: Ahmed-Mohamed Karim
Published: January 2012

This article argues that due to the fact that working in public bodies has become the preferred field of professional development for social workers, a certain level of stagnation in theory and professional practice has been produced. The conclusions emphasize the responsibility of professionals and academics in configuring different feedback between theory, practice and ethics, which increases the possibilities of social intervention.