bluuebunny/crossref_metadata_2025 huggingface dataset:
Infra‐red heating calculations with a water vapour pressure broadened continuum
Authors: Cox S. K.
Published: February 2007

Previous heat budget studies relying on infra‐red radiation calculations have not used a water vapour pressure dependent continuum absorption in the 830‐1,250 cm−1 region of the infra‐red spectrum. The purpose of this study was to investigate the differences in the infra‐red divergence profiles caused by inclusion of the vapour pressure dependent continuum absorption.

The results indicate only a very small change in infra‐red divergence from previous work for a typical midlatitude temperature, water vapour profile. However, for tropical temperature and moisture profiles, the new continuum data result in approximately 30 per cent more total tropospheric infra‐red cooling than obtained using earlier continuum absorption data. In addition, it is shown that within a realistic range of tropical atmosphere moisture content, the continuum infra‐red cooling may act to either stabilize or destabilize the lower layers of the troposphere.
Integrations of the primitive equations on a sphere using the finite element method
Authors: Cullen M. J. P.
Published: February 2007

Integrations of the shallow water equations on the sphere using the finite element method are performed and compared with published integrations of Doron et al. (1974). Better results are obtained with the finite element method than with a second order finite difference method using four times the number of grid points, in particular the breakdown of a Rossby wave of zonal wavenumber 8 is correctly predicted.
Gradient Richardson number profiles and changes within an intense mid‐tropospheric baroclinic zone
Authors: Bosart L. F. , Garcia O.
Published: February 2007

The three‐dimensional pattern of Richardson numbers in isentropic co‐ordinates is investigated for a case study of a mid‐tropospheric baroclinic zone for which special three‐hourly radiosonde data are available. Results show that the lowest Richardson number values are found within the baroclinic zone with most values between 0.25 and 1.0.

An equation developed by Roach (1970) was used to relate observed versus computed changes of d/dt (In Ri) in isentropic co‐ordinates throughout the baroclinic zone. In general stretching deformation contributed to an increase of In Ri in downstream regions of the baroclinic zone whereas the converse was true for shearing deformation in mid‐ and upstream regions of the baroclinic zone. Overall agreement between computed and observed changes ranged from poor outside the baroclinic zone to fair to good within the zone.

Air parcels entering the upstream region of the baroclinic zone underwent both frontogenesis and decrease in In Ri. The reverse was noted in the downstream region of the baroclinic zone.
Long‐wave radiation at the ground I. Angular distribution of incoming radiation
Authors: Unsworth M. H. , Monteith J. L.
Published: February 2007

The apparent emissivity of the atmosphere ϵ, defined as the ratio of incoming long‐wave radiation to black‐body radiation at screen temperature Ta, was measured under clear skies in the English Midlands and in the Sudan. At a zenith angle Z the emissivity was given by ϵ(Z) = a + bIn(usec Z) where u is the reduced depth of precipitable water (cm). For a set of 46 scans in England, the mean values of a and b were 0·70±0·05 and 0·090 ± 0·002. Systematic deviations about these mean values could be ascribed to: (i) temperature gradients; (ii) aerosol. The Sudan measurements gave a = 0·67 ± 0·03 and b = 0·085 ± 0·002 consistent with the English results and observations already published. There is some evidence that minimum values of a have increased over the past 50 years.

Integration over the hemisphere gives the flux density (Wm−2) of atmospheric radiation as 1·06 σTa4 − 119 (T in K), where σ is Stefan's constant, or 5·5 Ta + 213 (T in °C).

Radiation records by Dines and Dines (1927) for overcast skies are analysed to show that the angular distribution is the same as for cloudless skies; that the mean temperature of cloud base at their site was UK below screen temperature; and that when the mean fraction of cloud cover is c, the apparent emissivity is ϵa(c) = (1 − 0·84c)ϵa(0) + 0·84c.
The Risø profiles: A study of wind and temperature data from the 123‐m tower at Risø, Denmark
Authors: Peterson Ernest W.
Published: February 2007

A new study has been made of the Risø profiles with the following conclusions:

roughness lengths determined from neutral wind profiles selected by gradient Richardson number are biased towards high roughness lengths. Selecting the profiles by using a bulk Richardson number criterion yields average profiles with lower roughness lengths. This roughness length is relatively independent of stability while that determined from profiles using a gradient Richardson number is greater than the roughness lengths for either stable or unstable cases;

it is doubtful whether ‘double kinks’ in some of the Risø wind profiles are caused by local terrain inhomogeneities, as has previously been suggested;

three‐dimensionality and unknown mesoscale and baroclinic effects make it difficult if not impossible to compare current change‐of‐terrain theory with the Riø 123‐m tower data.
Theoretically determined multiple‐scattering effects of dust on Umkehr observations
Authors: Deluisi J. J. , Herman B. M. , Browning S. R. , Sato R. K.
Published: February 2007

An earlier theoretical treatment by DeLuisi (1967) of the optical effect of dust on Umkehr observations, yielded some differences from dust effects determined by an experimental method. The differences were thought to be due to errors in the observations used to obtain the experimental results, and the primary‐scattering restriction imposed on the theoretical calculations. A theoretical investigation was performed recently to assess the effect of multiple‐scattering in an atmosphere with dust. The new results are in better agreement with the experimental data and apparently explain nearly all the differences encountered with the theoretical primary‐scattering results.
A representation of the effects of topography on surface rainfall within moving baroclinic disturbances
Authors: Collier C. G.
Published: February 2007

A numerical ‘parameterization’ model has been developed in order to predict precipitation amount over hilly terrain in North Wales. The model enables calculations to be made of the vertical velocity profile resulting from orographic and large‐scale baroclinic effects at grid points one kilometre apart over an area of 2400km2. In the present study the precipitation falling on an area of 103km2, and on areas of order 102km2 within the larger area has been predicted, using as the input to the model large‐scale wind and humidity values derived from radiosonde ascents. Seven case studies are presented. All are examples of fast moving baroclinic systems. This type of system was chosen to minimize the effects of non‐orographic mesoscale or convective mechanisms, which are not parameterized in the present model. The mean error in the predicted rainfall over 103km2 was ± 10% and over 102km2 about ± 20%.
Global dynamics and climate ‐ a system of minimum entropy exchange
Authors: Paltridge G. W.
Published: February 2007

It is found that the mean meridional distribution of temperature, cloud cover and meridional energy flux can be predicted with extraordinary accuracy by application of a simple minimum principle to a multi‐box model of the globe which contains no direct specification of the system dynamics. The minimized quantity is related to the global net rate of production of entropy. It is the sum over all latitude zones of the ratio of net radiant energy input to the effective emission temperature of the zone. The result suggests that global dynamics is something of a passive variable which alters so as to satisfy a condition akin to minimum energy dissipation.
On the asymmetry of the land‐breeze sea‐breeze circulation
Authors: Pearson R. A.
Published: February 2007

Land‐ and sea‐breeze circulations are simulated in a mathematical model, using a stably stratified atmosphere as a basic state. The results show that the land‐breeze is weaker than the sea‐breeze even although the heat contrast at the coast is identical in both cases. This is consistent with estimates of the corresponding model energy available potential.
Evaporation and advection I: evaporation from extensive homogeneous surfaces
Authors: McNaughton K. G.
Published: February 2007

The process of modification of the Bowen ratio, with distance downwind of a change in surface wetness, is considered to establish the ratio of the fluxes of sensible and latent heat when unaffected by surface inhomogeneity. The case of steady‐state two‐dimensional advection is considered. It is shown that the coupled, simultaneous, diffusion equations for heat and moisture transfer from natural vegetated or wet surfaces can be used to generate two independent diffusion equations in composite variables. The vegetated surface is represented as an extensive single leaf. The height integral of the reciprocal effective eddy diffusivity is assumed to become indefinitely large with height so that heat and moisture continuously accumulate within the overpassing air. As a result equilibrium does not obtain. However, the surface latent heat flux approaches a quasi‐equilibrium value given, in conventional symbols, by LE = (s/(s+γ)) (Rn −G). For terrestrial surfaces, where the available energy depends only slightly on surface temperature, the Bowen ratio approaches γ/s. For deep water bodies and melting snow the heat flux into the surface also evolves with distance and the above relationship is approached only in the trivial sense that Rn = G and LE = 0. This model for terrestrial surfaces is consistent with some recent experimental observations.
On the entrainment rate of a stratocumulus‐topped mixed layer
Authors: Deardorff J. W.
Published: February 2007

The forced entrainment rate at the top of a stratocumulus deck is derived from the assumption that the negative buoyancy flux there is a particular fraction (1/2) of the average buoyancy flux within the entire mixed layer. A portion of the cloudtop radiative cooling is allowed to occur below the inversion base, thus contributing to the maintenance of the mixed‐layer turbulence. The derived equation clearly shows the dependence of the forced entrainment rate upon the surface heat and moisture fluxes, cloudtop radiative cooling rate, temperature and humidity jumps across the capping inversion, solar absorption rate within the mixed layer, and percentage of the mixed layer occupied by stratocumulus. The forced entrainment rate becomes inapplicable when the thermal jump at cloudtop becomes very small; then either encroachment or free entrainment occurs, and expressions are proposed for each. A useful criterion is that the entrainment rate is the minimum of the calculated rates for forced entrainment, encroachment, and free entrainment. The equation is tested satisfactorily against observations of coastal stratus off California and stratocumulus development over Lake Michigan.
Dynamics of climatic hazards in northeast Brazil
Authors: Hastenrath Stefan , Heller Leon
Published: February 2007

Departure characteristics of the large‐scale circulation are studied in relation to extreme drought and flood years in northeastern Brazil identified from a collective of long‐term rainfall stations and series of river discharge. Ship observations during 1911–72 compiled with a one degree square resolution and extending between 30°N and 30°S from the African coast to the eastern Pacific form a major observational basis.

The rainy season of northeastern Brazil is narrowly centred around March/April and is related to the southernmost seasonal migration of a lower‐tropospheric confluence axis over the adjacent eastern tropical Atlantic. the ‘Sěcas’ of Ceará province are characterized by an equatorward expansion of the South Atlantic, and a poleward retraction of the North Atlantic, high ‐ associated with a northward displacement of the enclosed near‐equatorial trough of low pressure. Concurrently, the zonally oriented bands of maximum cloudiness and precipitation frequency stay farther north, the North Atlantic trades weaken, and the South Atlantic trades become stronger than in the long‐term mean. the sea surface temperature pattern during a deficient rainy season in northeast Brazil is characterized by positive departures in a broad band across the North Atlantic and in the eastern Pacific, and anomalously cold waters in most of the South and equatorial Atlantic. During abundant rainy seasons in northeast Brazil, departure patterns are approximately inverse to those typical of drought years.

A strong negative linkage exists between northeast Brazil rainfall and sea surface temperature along the Ecuador/Peru coast. This seems to be caused by inverse long‐term pressure variations over the eastern South Pacific and South Atlantic oceans, which in turn may be part of large‐scale mass adjustments of the Southern Oscillation type.

Development of the equatorward expansions of the North and South Atlantic highs, pre‐season precipitation in northeast Brazil and the Guayanas, and location of the cloudiness and precipitation belts over the adjacent western tropical Atlantic, are among the more promising predictors for seasonal foreshadowing of extreme rainy season behaviour in northeast Brazil.
Characterization of impurities in spiramycin by liquid chromatography/ion trap mass spectrometry
Authors: Pendela Murali , Govaerts Cindy , Diana José , Hoogmartens Jos , Van Schepdael Ann , Adams Erwin
Published: February 2007

A reversed‐phase liquid chromatography/tandem mass spectrometry method is described for the investigation of spiramycin and related substances. The method uses an XTerra C18 column (250 × 4.6 mm i.d.), 5 µm, and a mobile phase consisting of acetonitrile, methanol, water and ammonium acetate solution, pH 6.5. Mass spectral data were acquired on an LCQ ion trap mass spectrometer equipped with atmospheric pressure chemical ionization (APCI) operated in the positive ion mode. Using this method, the fragmentation behavior of spiramycin and its related substances was studied and the unknown impurities occurring in commercial samples were investigated. In total 17 compounds were identified, among which three reported as specified impurities in the European Pharmacopoeia. The other impurities showed mainly a modification in the forosamine sugar or in the substituent at C‐3 and C‐6 positions. In one impurity, the mycarose sugar is absent. Copyright © 2007 John Wiley & Sons, Ltd.
Strategic alliance contracts: dimensions and determinants of contractual complexity
Authors: Reuer Jeffrey J. , Ariño Africa
Published: February 2007

In contrast to prior studies examining strategic alliances as discrete governance structures (e.g., alliances vs. M&A, equity vs. non‐equity agreements), we investigate their particular contractual features. The analysis examines the dimensionality of the contractual complexity construct and investigates the determinants of firms' adoption of various contractual provisions. We find two underlying dimensions of contractual complexity, based upon the enforcement and coordination functions of different contractual provisions. The evidence reveals that firms' usage of particular contractual provisions is a function of asset specificity as well as whether the alliance's duration is pre‐specified or open‐ended. The findings also speak to the debate surrounding the roles of prior ties and trust for alliance governance. Firms that have collaborated with each other in the past are not less likely to negotiate enforcement provisions; rather, repeat collaborators are less likely to adopt contractual provisions that are informational in nature and are geared to the coordination of the alliance. Copyright © 2007 John Wiley & Sons, Ltd.
Thurstonian-Based Analyses: Past, Present, and Future Utilities
Authors: Böckenholt Ulf
Published: February 2007

Current psychometric models of choice behavior are strongly influenced by Thurstone’s (1927, 1931) experimental and statistical work on measuring and scaling preferences. Aided by advances in computational techniques, choice models can now accommodate a wide range of different data types and sources of preference variability among respondents induced by such diverse factors as person-specific choice sets or different functional forms for the underlying utility representations. At the same time, these models are increasingly challenged by behavioral work demonstrating the prevalence of choice behavior that is not consistent with the underlying assumptions of these models. I discuss new modeling avenues that can account for such seemingly inconsistent choice behavior and conclude by emphasizing the interdisciplinary frontiers in the study of choice behavior and the resulting challenges for psychometricians.
The Times of Their Lives: from Chronological Precision to Kinds of History and Change
Authors: Whittle Alasdair , Bayliss Alex
Published: February 2007

In preparing for the publication of the seven papers in the special supplement of Cambridge Archaeological Journal, we were concerned to find an outlet that could find a worldwide audience, as we believe that these papers have more than regional or period significance. That is a big claim. The case studies presented in the supplement are all of early Neolithic long barrows and long cairns of the fourth millennium cal. bc in southern England. Why should a study of the dating of constructions that held the remains of selected human dead, from a particular region of northwest Europe, at a particular point in the regional Neolithic sequence, have any wider importance? We offer two reasons. First, we are applying, perhaps for the first time to a group of monuments rather than to individual sites, a method for the interpretation of radiocarbon dates which enables much more precise estimates of chronology. Secondly, from this promise of far more robust and precise dating come many implications for the kinds of agents that we may wish to people our pasts, for the kinds of lives they lived, and for the histories that we can try to write about them. These are two developments, we suggest, which any archaeology needs to embrace.
A Short Passage of Time: the Dating of the Hazleton Long Cairn Revisited
Authors: Meadows John , Barclay Alistair , Bayliss Alex
Published: February 2007

Forty-four radiocarbon results are now available from the Hazleton North long cairn, and are presented within an interpretive Bayesian statistical framework. Three alternative archaeological interpretations of the sequence are given, each with a separate Bayesian model. In our preferred model the cairn is considered to be a unitary construction, following on from the pre-cairn midden and other activity after a short interval during which the site was cultivated; bodies of the recently dead were subsequently interred in the chambered areas. Further human remains were deposited in the entrances to the chambers slightly later in the Neolithic, after the primary phase of use of the cairn for burials. This model suggests that the cairn was constructed in the first half of the thirty-seventh century cal. bc, and that its primary use for burial lasted for only two or three generations, ending probably in the 3620s cal. bc. A second model which varies only in postulating continuity between the pre-cairn activity and the cairn itself has poor overall agreement, suggesting that this interpretation is improbable. The third model explores the possibility that some of the human remains (those where the deposition of intact corpses cannot be strongly inferred from the archaeological record) may have been curated for a considerable time since death when deposited in the tomb. This interpretation suggests a slightly later date for the construction of the cairn, in the middle decades of the thirty-seventh century cal. bc, and suggests that any human remains which were not interred as corpses were less than a century old when deposited. The correspondence between the bones most likely, on chronological grounds, to be ‘ancestral’ and those most likely, on archaeological grounds, not to have been deposited as intact corpses is, however, poor. For this reason we feel there is no clear evidence that the human remains at Hazleton were not deposited shortly after the deaths of the individuals concerned, and we prefer model 1.
Effect of maturation medium onin vitrocleavage of canine oocytes fertilized with fresh and cooled homologous semen
Authors: Rodrigues B. de Ávila , dos Santos L. Carboneiro , Rodrigues J.L.
Published: February 2007

This study evaluated the effect of three maturation media on the development ofin vitro-matured andin vitro-fertilized dog oocytes. In Experiment 1 (non-comparative experiment) canine cumulus–oocyte complexes (COCs) were maturedin vitroin TCM199 supplemented with estrous cow serum (10%) + gonadotropins + steroid (treatment A), TCM199 + estrous cow serum (10%) (treatment B), or TCM199 + polyvinylpyrrolidone (PVP) (4%) (treatment C). All maturation media contained a final concentration of 1 μg/ml of human somatotropin (hST). Oocytes were fertilized with fresh ejaculated sperm and development was assessed by cleavage. The objective of Experiment 2 (comparative experiment) was to compare the rates of cleavage and developmental capacity of COCs maturedin vitroin same medium as in Experiment 1, and fertilized either with fresh ejaculated or with cooled extended homologous spermatozoa. In Experiments 1 and 2, oocytes fertilized with fresh semen werein vitro-matured for 48 h, while in Experiment 2 COCs fertilized with cooled semen were maturedin vitrofor 72 h. The results of Experiments 1 and 2 demonstrated that cleavage was not influenced by the oocyte's maturation environment. The results of Experiment 1 showed that pronucleus formation + cleavage (day 7 after IVF) was similar among treatments A, B and C (p= 0.277). Also, in Experiment 2, pronucleus formation + cleavage (day 7 after IVF) was not different for oocytes fertilizedin vitroeither with fresh or cooled semen and maturated in media A (p= 0.190), B (p= 0.393) or C (p= 0.687). In both experiments, the numbers of embryos that developed to the 6–8-cell stage were higher for oocytes matured in medium A and fertilized with fresh semen, when compared with numbers of oocytes matured in media B and C. Embryo development to the 6–8-cell stage of oocytes fertilized either with fresh or cooled sperm was observed in treatments A and C in Experiment 2. Cumulus cell expansion was similar among treatments in Experiment 1. In Experiment 2, cumulus cell expansion among treatments A, B and C was similar after 48 h or 72 h of IVM. In both experiments, the greatest expansion category seen was for category 2 (outer cumulus cells slightly expanded). No correlation between cumulus expansion and cleavage were observed. Polyspermy rates in oocytes matured in medium A, and fertilized with fresh sperm were not significantly different from polyspermy rates observed using media B and C, in both experiments. Our findings indicate that treatments A, B and C are similarly effective for the cleavage of dog oocytes. Furthermore, it was demonstrated that canine oocytes maturedin vitrocould be fertilized by homologous cooled spermatozoa and progress to cleavage.
Observations of the diurnal cycle of outgoing longwave radiation from the Geostationary Earth Radiation Budget instrument
Authors: Comer Ruth E. , Slingo Anthony , Allan Richard P.
Published: February 2007

The Geostationary Earth Radiation Budget instrument on Meteosat‐8, located over Africa, provides unprecedented temporal sampling (∼17 minutes) of the broadband emitted thermal and reflected solar radiances. We analyse the diurnal cycle of the outgoing longwave radiation (OLR) fluxes derived from the thermal radiances for July 2006. Principal component (PC) analysis separates the signals of the surface temperature response to solar heating and of the development of convective clouds. The first two PCs explain most of the OLR variations: PC1 (surface heating) explains 82.3% of the total variance and PC2 (cloud development) explains 12.8% of the variance. Convection is initiated preferentially over mountainous regions and the cloud then advects downstream in the ambient flow. Diurnal variations are much weaker over the oceans, but a coherent signal over the Gulf of Guinea suggests that the cloudiness is modulated by the diurnally varying contrast between the Gulf and the adjacent land mass.
Evidence for N2O ν3 4.5 μm non‐local thermodynamic equilibrium emission in the atmosphere
Authors: López‐Puertas M. , Funke B. , Bermejo‐Pantaleón D. , von Clarmann T. , Stiller G. P. , Grabowski U. , Höpfner M.
Published: February 2007

We present a clear evidence for N2O 4.5 μm non‐local thermodynamic equilibrium (non‐LTE) emissions in the daylight stratosphere and mesosphere from measurements by the MIPAS experiment on board Envisat. We have used non‐LTE radiative transfer models in order to quantify the magnitude and extent of the non‐LTE deviation of N2O(001) in the Earth's atmosphere. The departure from LTE in N2O during daytime commences at altitudes around 40–50 km, but have significant effects (10%) on daytime limb radiance down to tangent heights of 20 km. The enhancement increases rapidly with altitude, being 20–80% at 50 km, and reaching factors of 2–8 in the lower mesosphere. This study shows that the enhancement is mainly produced by absorption of solar radiation by N2O at 4.5 μm and by V‐V collisions with N2(1). Non‐LTE effects are also significant at nighttime, where LTE calculations overpredict N2O radiances by 10–20% at 40–55 km tangent heights.
Measurements of heterogeneous ice nuclei in the western United States in springtime and their relation to aerosol characteristics
Authors: Richardson Mathews S. , DeMott Paul J. , Kreidenweis Sonia M. , Cziczo Daniel J. , Dunlea Edward J. , Jimenez Jose L. , Thomson David S. , Ashbaugh Lowell L. , Borys Randolph D. , Westphal Douglas L. , Casuccio Gary S. , Lersch Traci L.
Published: February 2007

The second Ice Nuclei Spectroscopy (INSPECT‐II) campaign was conducted at Storm Peak Laboratory in northwestern Colorado in April and May 2004. The physical and chemical characteristics of springtime atmospheric aerosols, including those which act as heterogeneous ice nuclei (IN), were investigated. The ice formation activity of submicron particles was measured with a continuous‐flow diffusion chamber. The concentrations of heterogeneous ice nuclei ([IN]) active at −15 to −50°C and water supersaturations −25% < SSw < 0 typically ranged from 1 to 10 std l−1. Aerosol mass spectrometry measurements indicated that the composition of IN had much higher contributions from mineral dust/fly ash and metallic particle types compared to ambient particles of similar sizes. While IN concentration and composition measurements are similar to observations from the same site during INSPECT‐I in November 2001, there was considerably more variability in [IN] during INSPECT‐II associated with periods of sporadically high [IN]. A relation of [IN] to concentrations of larger particles was noted; however, the predictive utility of such a relationship proved limited during non‐dust‐related increases in accumulation mode number concentrations. We conclude that the observed high variability and extremes in [IN] during spring are attributable primarily to variations in airborne dust concentrations and that the [IN] observed in spring 2004 represent lower bounds on the expected [IN] at SPL in the spring. On the basis of modeled dust vertical profiles, strong impacts of dust on [IN] might be expected at the higher altitudes of cold clouds.
Mouse respiratory tract dendritic cell subsets and the immunological fate of inhaled antigens
Authors: Wikstrom Matthew E , Stumbles Philip A
Published: February 2007

It is widely accepted that tissue dendritic cells (DC) function as immune sentinels by alerting T cells to foreign antigen after delivering and presenting it in the draining lymph nodes. Over the last two decades, studies in animal models, particularly rodents, have demonstrated that respiratory tract DC are crucial for the adaptive immune response to inhaled antigen. Indeed, the fate of inhaled antigen is inextricably linked to the function of respiratory tract DC. In this review, we will discuss the characteristics of respiratory tract DC from mice and recent data that may help to explain their role in the fate of inhaled antigen.
Effect of nonstoichiometry on the thermoelectric properties of a Ag2Se alloy prepared by a mechanical alloying process
Authors: Lee Changho , Park Yong-Ho , Hashimoto Hitoshi
Published: February 2007

The effect of nonstoichiometry on the thermoelectric properties of a Ag2Se alloy prepared by a mechanical alloying and pulse discharge sintering process has been investigated. The x-ray diffraction pattern confirms that the Ag2Se alloy was synthesized by using a mechanical alloying process. The thermal conductivity and the figure-of-merit (Z) value of the Ag2Se alloy was 0.65 W∕K m and 0.282×10−3∕K, respectively. Both the Z values of the excess Ag and excess Se alloy were much higher than that of Ag2Se alloy, probably the result of the increased power factor. However, the mechanism for the increase is different with the alloy type. In the case of the excess Ag alloy, the carrier concentration was increased by the excess amount of pure Ag atoms and/or clusters, resulting in an increase in electrical conductivity. To the contrary, for the excess Se alloy, the Hall mobility, which has a crucial effect on Z value, was increased because of the low carrier concentration. As a result, the Z value was improved from 0.282×10−3∕K (Ag2Se) to 0.912×10−3∕K (Ag2.05Se0.95) and 2.016×10−3∕K (Ag1.975Se1.025). Thus, the thermoelectric Z value for silver selenide can be dramatically increased by the presence of a small, nonstoichiometric amount of Ag or Se.
Atomistic nature of NaCl nucleation at the solid-liquid interface
Authors: Yang Yong , Meng Sheng
Published: February 2007

The early stage of heterogeneous nucleation of NaCl from supersaturated NaCl aqueous solution at the water-NaCl (001) interface has been investigated by molecular dynamics simulations. The critical size of the nuclei for spontaneous growth was found to be as small as two atoms (a Na+–Cl− ion pair) at high supersaturation. Due to the presence of a relatively stable water network and the effect of the hydration force at the interface, the stable nuclei formed on the NaCl (001) are found to contain more Na+ ions than Cl− ions. The different deposition characteristics of the Na+ and Cl− solutes lead to a positively charged substrate and thus may introduce another driving force for nucleation besides the level of solution supersaturation. The role of water was further confirmed by comparison with NaCl epitaxy growth in the vacuum.
Impact of interfacial roughness on tunneling conductance and extracted barrier parameters
Authors: Miller Casey W. , Li Zhi-Pan , Åkerman Johan , Schuller Ivan K.
Published: February 2007

The net tunneling conductance of metal-insulator-metal tunnel junctions is studied using a distribution of barrier thicknesses consistent with interfacial roughness typical of state-of-the-art tunnel junctions. Moderate amounts of roughness cause the conductance to resemble that of much thinner and taller barriers. Fitting numerically generated conductance data that include roughness with models that assume a single-thickness barrier leads to erroneous results for both the barrier height and width. Rules of thumb are given that connect the roughness to the real space mean thickness and the thickness inferred from fitting the net conductance with traditional tunneling models.
Magnetic studies of GaN nanoceramics
Authors: Zaleski A. J. , Nyk M. , Strek W.
Published: February 2007

The synthesis, morphology, and magnetization measurements of GaN nanoceramics obtained under high pressure are reported. In particular, the effect of grain size on magnetic properties of GaN nanopowders and nanoceramics was investigated. It was found that for the GaN nanoceramic characterized by the stronger deformation of nanocrystalline grains, the diamagnetic signal changes with external magnetic field similarly to the Meissner effect in superconductors.
Study of the effects of an AlN interlayer on the transport properties of AlGaN∕AlN∕GaN heterostructures grown on SiC
Authors: Elhamri S. , Mitchel W. C. , Mitchell W. D. , Landis G. R. , Berney R. , Saxler A.
Published: February 2007

Transport measurements were used to characterize AlGaN∕AlN∕GaN∕SiC. While the carrier concentration, n=9.2×1012cm−2, remained relatively unchanged from 300 down to 1.2K, the mobility increased from 2100 to over 3×104cm2∕Vs. Shubnikov-de Haas oscillations were observed in fields as low as 2T. Despite the high n, quantum Hall plateaus, which are rarely reported in conventional AlGaN∕GaN with comparable n, were observed. The calculated quantum scattering time of 0.28ps is longer than what is typically reported for conventional AlGaN∕GaN. This improvement is believed to be due to a reduction in alloy scattering.
Charge transfer effect in the polyaniline-gold nanoparticle memory system
Authors: Tseng Ricky J. , Baker Christina O. , Shedd Brian , Huang Jiaxing , Kaner Richard B. , Ouyang Jianyong , Yang Yang
Published: February 2007

A composite system comprised of polyaniline nanofibers bonded with gold nanoparticles is shown to possess a memory effect via a charge transfer mechanism. The charge transfer occurs between the imine nitrogen in the polyaniline and the gold nanoparticles as confirmed by x-ray photoelectron spectroscopy and Raman spectroscopy. This charge transfer enables a bistable electrical conductivity, allowing the material system to be used as a digital memory device. The charge transfer is further confirmed by the elimination of the conductance switching when the fully reduced form of polyaniline, leucoemeraldine, which possesses no imine nitrogens, is used in place of the emeraldine form.
Viscous relaxation of drift-Alfvén waves in tokamaks and its application for triggering improved confinement regimes
Authors: Tsypin V. S. , Elfimov A. G. , Galvão R. M. O.
Published: February 2007

Viscous damping of the drift-Alfvén modes in tokamaks and its application for triggering improved confinement regimes are considered. It is shown that these waves are effectively damped by the neoclassical viscosity with the upper limit for their frequency ω equal to the collision frequency of slow ions νi∕ϵ, where ϵ is the inverse aspect ratio. Quasistationary plasma poloidal and toroidal velocities and current drive produced by damping of these waves are estimated. Evaluations of the viscosity effects on the Alfvén waves which were induced by the dynamic ergodic divertor in the Tokamak Experiment for Technology Oriented Research tokamak [K. H. Finken et al., Phys. Rev. Lett. 94, 015003 (2005)] are made.
Kinetic study of Al-mole fraction in AlxGa1−xN grown on c-plane sapphire and AlN bulk substrates by metal-organic vapor-phase epitaxy
Authors: Xi Y. A. , Chen K. X. , Mont F. W. , Kim J. K. , Lee W. , Schubert E. F. , Liu W. , Li X. , Smart J. A.
Published: February 2007

A systematic study is performed on the dependence of the Al-mole fraction in AlxGa1−xN on the organometallic group-III precursor flow during metal-organic vapor-phase epitaxy. When keeping the total organometallic volume flow constant, a nonlinear concave bowing relationship is found between the Al-mole fraction (for 0⩽x⩽1) and the relative trimethylaluminum volume flow. A kinetic model, which takes into account the growth rate ratio between GaN and AlN (gGaN∕gAlN), is developed to explain such concave bowing relationship. The experimental data are in excellent agreement with the theoretical model. For AlxGa1−xN growth on AlN bulk substrates, it is found that the Al-mole fraction is smaller and the growth rate ratio is larger than on sapphire substrates. The authors also investigate the incorporation of Al in AlxGa1−xN as a function of the group-III precursor molar flow rate. A positive convex bowing relationship is found between Al-mole fraction and the relative trimethylaluminum molar flow, which is consistent with our model.
Distribution and reproductive biology of the sandbar shark, Carcharhinus plumbeus (Nardo), in Western Australian waters
Authors: McAuley R. B. , Simpfendorfer C. A. , Hyndes G. A. , Lenanton R. C. J.
Published: February 2007

In total, 7497 sandbar sharks, Carcharhinus plumbeus (Nardo, 1827), were collected between May 2000 and June 2003 from commercial fishers and during fishery-independent research cruises in coastal Western Australian waters. Maximum observed lengths were 165 and 166 cm fork length (FL) for males and females respectively. The lengths at which 50% of sharks were mature were 126.9 and 135.9 cm FL for males and females respectively. Juvenile sharks tended to occur in temperate waters, whereas mature-sized sharks predominantly occurred in tropical waters. Unlike other regions, juveniles were found in offshore continental shelf waters rather than in shallow waters of estuaries and marine embayments. Results indicated a biennial reproductive periodicity. Mating occurred during summer and autumn, and parturition took place after a 12-month gestation. Pups were born at 40 to 45 cm FL throughout most of the species’ Western Australian range. The majority of neonates were caught at temperate latitudes. Litter sizes varied between 4 and 10, with a mean of 6.5. There was a weak but statistically significant increase in litter size with maternal length. Mean embryonic sex ratio of females to males differed significantly from a one-to-one ratio.
Hierarchy of Notch–Delta interactions promoting T cell lineage commitment and maturation
Authors: Besseyrias Valerie , Fiorini Emma , Strobl Lothar J. , Zimber-Strobl Ursula , Dumortier Alexis , Koch Ute , Arcangeli Marie-Laure , Ezine Sophie , MacDonald H. Robson , Radtke Freddy
Published: February 2007

Notch1 (N1) receptor signaling is essential and sufficient for T cell development, and recently developed in vitro culture systems point to members of the Delta family as being the physiological N1 ligands. We explored the ability of Delta1 (DL1) and DL4 to induce T cell lineage commitment and/or maturation in vitro and in vivo from bone marrow (BM) precursors conditionally gene targeted for N1 and/or N2. In vitro DL1 can trigger T cell lineage commitment via either N1 or N2. N1- or N2-mediated T cell lineage commitment can also occur in the spleen after short-term BM transplantation. However, N2–DL1–mediated signaling does not allow further T cell maturation beyond the CD25+ stage due to a lack of T cell receptor β expression. In contrast to DL1, DL4 induces and supports T cell commitment and maturation in vitro and in vivo exclusively via specific interaction with N1. Moreover, comparative binding studies show preferential interaction of DL4 with N1, whereas binding of DL1 to N1 is weak. Interestingly, preferential N1–DL4 binding reflects reduced dependence of this interaction on Lunatic fringe, a glycosyl transferase that generally enhances the avidity of Notch receptors for Delta ligands. Collectively, our results establish a hierarchy of Notch–Delta interactions in which N1–DL4 exhibits the greatest capacity to induce and support T cell development.
Infection Control Dogma Among Nurses in Iran
Authors: Weed Harrison G. , Askarian Mehrdad
Published: February 2007

Using 33 dogmatic statements about infection control, we assessed the knowledge of infection control nurses at a conference in Iran and compared their responses with those of infection control nurses at a conference in the United States. A majority of those at the Iran conference responded correctly to 11 (33%) of 33 statements, whereas a majority at the US conference responded correctly to 20 (61%) of the statements. The differences in responses were significant (P < .001). Nurses at the Iran conference were more likely to agree with dogma not supported by the literature and to put more faith in general cleanliness to prevent infection than is supported by the literature. A similar questionnaire survey might be useful in countries like Iran that are developing their infection control personnel and infrastructure.
Influenza Vaccination Rates and Motivators Among Healthcare Worker Groups
Authors: Christini Amanda Banks , Shutt Kathleen A. , Byers Karin E.
Published: February 2007

Background.

The rate of influenza vaccination among healthcare workers (HCWs) is approximately 40%. Differences in vaccination rates among HCW groups and reasons for accepting or rejecting vaccination are poorly understood.

Objectives.

To determine vaccination rates and motivators among different HCW groups during the 2004-2005 influenza season.

Design.

Cross-sectional survey conducted between July 10 and September 30, 2005.

Setting.

Two tertiary care teaching hospitals in an urban center.

Participants.

Physicians, nurses, nursing aides, and other staff. Surveys were collected from 1,042 HCWs (response rate, 42%).

Results.

Sixty-nine percent of physicians (n = 282) and 63% of medical students (n = 145) were vaccinated, compared with 46% of nurses (n = 336), 42% of nursing aides (n = 135), and 29% of administrative personnel (n = 144). Physicians and medical students were significantly more likely to be vaccinated than all other groups (P < .0001). Pediatricians (84%) were more likely than internists (69%) and surgeons (43%) to be vaccinated (P < .0001). Among the HCWs who were vaccinated, 33.4% received the live attenuated influenza vaccine (LAIV) and 66.6% received trivalent inactivated influenza vaccine (TIV). Vaccinated HCWs were less likely than unvaccinated HCWs to report an influenza-like illness (P = .03). Vaccination with LAIV resulted in fewer episodes of influenza-like illness than did receiving no vaccine (P = .03). The most common reason for rejecting vaccination was a concern about availability. Understanding that HCWs may transmit the virus to patients correlated with vaccine acceptance (P = .0004).

Conclusions.

Significant differences in vaccination exist among physician specialties and employee groups, and there are inadequate vaccination rates among those with the greatest amount of patient contact, potentially providing a basis for group-specific interventions.
The degree of the bicanonical map of a surface with 𝑝_{𝑔}=0
Authors: Mendes Lopes Margarida , Pardini Rita
Published: February 2007

In this note it is shown that, given a smooth minimal complex surface of general type

S
S

with

p
g

(
S
)
=
0

p_g(S)=0

,

K
S
2

=
3

K^2_S=3

, for which the bicanonical map

φ

2
K

\varphi _{2K}

is a morphism, the degree of

φ

2
K

\varphi _{2K}

is not 3. This completes our earlier results, showing that if

S
S

is a minimal surface of general type with

p
g

=
0

p_g=0

,

K
2

≥
3

K^2\ge 3

such that

|

2

K
S

|

|2K_S|

is free, then the bicanonical map of

S
S

can have degree 1, 2 or 4.
Social Control in Marital Relationships: Effect of One's Partner on Health Behaviors1
Authors: Lewis Megan A. , Butterfield Rita M.
Published: February 2007

The present study examined the role that health‐related social control plays in promoting health‐enhancing behavioral reactions among married couples. Health‐related social control refers to interactions entailing influence and regulation of health practices. A sample of 109 couples answered questions about their social control interactions during structured phone interviews. Analyses maintaining the couple as the unit of analysis indicated that spouses' reports of more frequent social control overall and the use of positive, bilateral, and direct social control tactics predicted their partners' reports of health‐enhancing behavioral reactions.
Depression, Stress, and Blood Pressure in Urban African‐American Women
Authors: Artinian Nancy T. , Washington Olivia G.M. , Flack John M. , Hockman Elaine M. , Jen Kai‐Lin Catherine
Published: February 2007

African‐American women have disturbingly high rates of hypertension, exceeding those of African‐American men and other ethnic groups. Reasons for these disparities are not understood. Depression, more common in women than men, has been linked to endothelial dysfunction, inflammation, metabolic and hematologic abnormalities, and increased sympathetic nervous system activity—all factors associated with cardiovascular disease. A descriptive correlational design was used to test the following hypotheses: 1) African‐American women with higher levels of depression will have higher blood pressure (BP) levels, more cardiovascular risk factors, greater stress, and lower social support; and 2) depression will mediate the relationship between stress and BP. A convenience sample of 245 hypertensive African‐American women (mean age, 61 ±12.7 years) was recruited through free BP screenings offered in the community. All data were collected during a structured interview and brief physical examination. Pearson r correlation coefficients, analysis of variance, and multiple regression analyses were used to analyze the hypotheses. Women with higher levels of depression had higher diastolic BP and were more likely to smoke, eat fewer fruits and vegetables, and have more stress and less social support. Depression mediated the relationship between stress and diastolic BP. The findings emphasize the importance of assessing both behavioral and psychosocial factors in urban African‐American women with hypertension.
The Relationship Between Spirituality and Compliance in Patients With Heart Failure
Authors: Black Gladys , Barbara A. Davis PhD, RN  , Kim Heathcotte RN, BSN  , Nikki Mitchell RN, BSN  , Charlotte Sanderson RN
Published: February 2007

A high incidence of noncompliance to prescribed treatment plans results in increased morbidity, hospitalizations, and mortality rates in patients with heart failure. Exploration of new avenues to encourage adherence is needed in nursing research. The purpose of this study was to explore whether a relationship existed between spirituality and compliance in patients with heart failure. The Spiritual Assessment Scale and the Heart Failure Compliance Questionnaire Revised were mailed to a convenience sample with a return response from 95 participants. Although mean scores for the Spiritual Assessment Scale and the Heart Failure Compliance Questionnaire Revised were high, data suggested no correlation existed between levels of spirituality and degree of compliance among the heart failure participants, r=16393; p=0.115. Although insignificant results were found between levels of spirituality and degree of compliance, the data did not rule out the importance of spirituality as a coping tool.
Angiogenesis‐related growth factors and cytokines in the serum of patients with B non‐Hodgkin lymphoma; relation to clinical features and response to treatment
Authors: PASSAM F. H. , SFIRIDAKI A. , PAPPA C. , KYRIAKOU D. , PETRELI E. , ROUSSOU P. A. , ALEXANDRAKIS M. G.
Published: February 2007

Increased angiogenesis has been shown to be a feature of non‐Hodgkin lymphomas (NHL). In the current study, the pretreatment levels of circulating molecules related to angiogenesis were determined in 49 B‐cell NHL patients and correlated with histological grade, disease stage and prognostic score. In 25 patients, the same molecules were defined after standard treatment. Vascular endothelial growth factor (VEGF), angiogenin, interleukin‐2 (IL‐2), IL‐6, IL‐8 and IL‐16 were measured. Increased levels of VEGF, IL‐6 and IL‐8 were found in the whole group of untreated patients in comparison with normal controls (P < 0.05), whereas, IL‐2 was higher in the subgroup of indolent NHL. Overall, there was no significant decrease in the levels of these molecules after treatment. However, by stratification into group of responders vs. non‐responders pretreatment IL‐8 was significantly increased whereas IL‐16 was decreased in the subgroup of complete responders. According to the REAL classification IL‐2 was higher in the low risk compared with intermediate plus high‐risk group. There was no association with disease stage or the International Prognostic Score. Both indolent and aggressive B cell lymphomas have increased production of angiogenic mediators and cytokines with IL‐8 and IL‐16 potentially reflecting the response to treatment.