bluuebunny/crossref_metadata_2025 huggingface dataset:
Applying Statistical Design of Experiments and Automation to the Rapid Optimization of Metal-Catalyzed Processes in Process Development
Authors: McWilliams J. Christopher , Sidler D. Richard , Sun Yongkui , Mathre David J.
Published: December 2005

The application of automation in conjunction with DoE designs towards the rapid discovery and optimization of metal-catalyzed reactions used in the synthetic preparation of clinical drug candidates at Merck Process Research is demonstrated with three examples. A description of the software and hardware is provided, followed by three examples highlighting these applications. The first example highlights a DoE optimization of a platinum-catalyzed chemoselective hydrogenation of a nitroaromatic nitrile. In the second example, automated screening is employed to discover a highly efficient palladium catalyst that affects nitrostyrene cyclization under a carbon monoxide reducing atmosphere. In the last example, a rapid discovery and DoE optimization of a rhodium-catalyzed diastereoselective hydrogenation of an unsaturated ester is detailed.
Three Steps to Heaven? Tensions in the Management of Welfare: Retirement Pensions and Active Consumers
Authors: MANN KIRK
Published: December 2005

This article explores some of the emerging tensions in the management of welfare in Britain. The success of Labour's proposals for welfare reform, particularly retirement pensions, hinges on their ability to promote the idea of the consumer citizen and to undermine traditional ideas of citizenship rights. However, managing this transition – including the presentation of ideas and the management of consumers – has not been straightforward. While the Government presents retirement as a matter of lifestyle choice, welfare ‘consumers’ are demanding more of their providers and are regularly disgruntled with the response.

Simultaneously, pension providers are expressing reservations about their ability to manage aggrieved consumers. Furthermore, they believe pension fund management has been politicised, and their scope for discretion reduced by regulation, while technical and scientific developments in terms of portfolio management and risk assessment have changed the working practices of those in the pension industry. These tensions between consumers, providers and legislators may generate further dissatisfaction with the balance of rights and responsibilities being hotly contested.
Perceptions of Risk in Intimate Relationships: The Implications for Social Provision
Authors: LEWIS JANE
Published: December 2005

The erosion of the traditional, male breadwinner model family – both normatively and in social reality – has opened up the possibility of more choice in terms of both partnering and the nature of the contributions that men and women make to households, but processes of ‘individualisation’ have also given rise to greater uncertainty.

We know relatively little about how people perceive their options for partnering, re-production and employment at the level of the household, and in particular what they are prepared to ‘take a chance on’, and what kind of security they seek. Yet this is important for policy purposes, particularly in view of the rapid pace of family and labour market change.

This article first addresses the kind of considerations that are necessary for a better understanding of the nature of risks and uncertainty arising from processes of individualisation. The substantive sections that follow draw on in-depth interviews with a heterogeneous sample of 21 cohabiting and married men and women, drawn from an Omnibus representative sample survey. The extent to which individuals regard partnering and childbearing as risks, and how they seek to manage them are explored and the implications for policy assessed.
Haemolytic uraemic syndrome associated with interfamilial spread of E. coli O26:H11
Authors: SAYERS G. , McCARTHY T. , O'CONNELL M. , O'LEARY M. , O'BRIEN D. , CAFFERKEY M. , McNAMARA E.
Published: December 2005

In September 2000, haemolytic uraemic syndrome (HUS) was diagnosed in a 10-month-old child with a prodromal history of vomiting and diarrhoea (non-bloody). Investigation revealed that a self-limiting gastrointestinal illness (mean duration 48 h) had occurred among immediate and extended family in the 2 weeks prior to the child's admission. The epidemiology of the illness suggested person-to-person spread. Five children (close family contacts) had E. coli O26 verocytotoxin (VT1 and VT2) isolated from stools. Stool culture and serology from the index case were negative for shiga toxin-producing E. coli (STEC) organisms. Control measures in accordance with the Public Health Laboratory Service (PHLS), verocytotoxogenic organisms (VTEC) guidelines were applied to prevent further spread among the extended family and contacts. Despite detailed food and environmental exposure histories, the source of the illness was not identified. This incident highlights the importance of investigation of cases of post-diarrhoeal HUS, for potential shiga toxin E. coli aetiology.
Vaccination coverage in adults undergoing splenectomy: evaluation of hospital vaccination policies
Authors: BRUNI L. , BAYAS J. M. , VILELLA A. , CONESA A.
Published: December 2005

Vaccination coverage in 595 adult patients undergoing total splenectomy in the Hospital Clinic of Barcelona during 1992–2002 was studied. The rates of cover for pneumococcal, Haemophilus influenzae type b and meningococcal vaccines were 63, 63 and 61% respectively, during 2000–2002; 32, 17 and 22% in 1997–1999; and 24, 9 and 8% in 1992–1996. Multivariate analysis showed a greater risk of no vaccination in splenectomies due to trauma, malignant neoplasms of solid organs and incidental splenectomy compared with both neoplastic and non-neoplastic haematological disease, and those patients undergoing splenectomy before 2001. Coverage ([ges ]1 vaccine) since 1997 in patients with haematological diseases was 83·5% (71/85), haematological neoplasias 69·2% (18/26), solid organ neoplasms 38·3% (36/94), incidental splenectomy 35·6% (16/45), and traumas 28·4% (21/74). Mandatory hospital admission of patients undergoing splenectomy offers a good opportunity for vaccination of these patients. Specific vaccination policies should be developed to take advantage of this circumstance.
Social and Economic Burden of Suicides in Hong Kong SAR
Authors: Yip P.S.F. , Liu Ka Y. , Law C.K. , Law Y.W.
Published: December 2005

Abstract. The paper proposes to use the years-of-life-lost method (YLL) in assessing the social and economic burden of suicides in Hong Kong SAR. The YLL from suicide by age group in 1981-2002 is calculated based on the standard set by World Health Organization (WHO). It shows that the middle age group (25-39) contributed most to the burden of disease in Hong Kong. The proportion of older adults' suicides is about 25% of the total number of suicides but its disease burden is less than 6% in terms of the YLL. Though the group aged 25-39 contributed disproportionately to the total YLL from suicide, the prevention effort for this particular group has been very much neglected and needs to be strengthened. It illustrates that use of YLL could provide a new viewpoint for setting up public health policies.
Crisis Occurrence and Resolution in Patients with Severe and Persistent Mental Illness
Authors: Links Paul S. , Eynan Rahel , Ball Jeffrey S. , Barr Aiala , Rourke Sean
Published: December 2005

Abstract. Assertive community treatment appears to have limited impact on the risk of suicide in persons with severe and persistent mental illness (SPMI). This exploratory prospective study attempts to understand this observation by studying the contribution of suicidality to the occurrence of crisis events in patients with SPMI. Specifically, an observer-rated measure of the need for hospitalization, the Crisis Triage Rating Scale, was completed at baseline, crisis occurrence, and resolution to determine how much the level of suicidality contributed to the deemed level of crisis. Second, observer-ratings of suicidal ideation, the Modified Scale for Suicide Ideation, and psychopathology and suicidality, Brief Psychiatric Rating Scale, were measured at baseline, crisis occurrence, and resolution. A self-report measure of distress, the Symptom Distress Scale, was completed at baseline, crisis occurrence, and resolution. Finally, the patients' crisis experiences were recorded qualitatively to compare with quantitative measures of suicidality. Almost 40% of the subjects experienced crisis events and more than a quarter of these events were judged to be severe enough to warrant the need for hospitalization. Our findings suggest that elevation of psychiatric symptoms is a major contributor to the crisis occurrences of individuals with SPMI; although the risk of suicide may have to be conceived as somewhat separate from crisis occurrence.
Mass Homicide and Suicide
Authors: Lester David , Stack Steven , Schmidtke Armin , Schaller Sylvia , Müller Ingrid
Published: December 2005

Abstract. A study of 98 lone, rampage killers in the United States from 1949 to 1999 found that those who were killed by police officers killed and wounded more victims than those who completed suicide who, in turn, killed or wounded more victims than those who were captured. Those rampage killers who completed suicide were less likely to be judged schizophrenic and more likely to be killing present or former co-workers.
Coseismic deformation of the 2001 Mw = 7.8 Kokoxili earthquake in Tibet, measured by synthetic aperture radar interferometry
Authors: Lasserre C. , Peltzer G. , Crampé F. , Klinger Y. , Van der Woerd J. , Tapponnier P.
Published: December 2005

The 14 November 2001, Mw = 7.8, Kokoxili earthquake ruptured more than 400 km of the westernmost stretch of the left‐lateral Kunlun fault in northern Tibet. Interferometric synthetic aperture radar data from descending orbits, along four adjacent tracks covering almost the entire rupture, and 1‐m pixel Ikonos satellite images are used to map the rupture geometry and the surface displacements produced by the event. Interferograms are then inverted to solve for coseismic slip on the fault at depth. The radar data show that the rupture connected the Heituo fault, where the earthquake initiated, to the main Kunlun fault, cutting across a pull‐apart trough in between the two strike‐slip faults. The fault model includes two vertical sections extending to a depth of 20 km and discretized into 5 km × 5 km patches. Using a nonnegative least squares method that includes an appropriate degree of smoothing, we solve for the left‐lateral slip on each fault patch. Our solution shows that the largest slip occurred at depths between 0 and 5 km, reaching ≃8 m in two areas, 200 and 250 km east of the earthquake epicenter. Significant slip took place below 10 km at both ends of the rupture. Slip appears to have been highly variable along the fault, defining six sections of major moment release. These sections correspond to six subsegments of the Kunlun fault system, defined from the surface morphology of the fault. This suggests that fault geometry exerted a predominant influence on controlling the rupture propagation.
A computationally efficient Multicomponent Equilibrium Solver for Aerosols (MESA)
Authors: Zaveri Rahul A. , Easter Richard C. , Peters Leonard K.
Published: December 2005

Development and application of a new Multicomponent Equilibrium Solver for Aerosols (MESA) is described for systems containing H+, NH4+, Na+, Ca2+, SO42−, HSO4−, NO3−, and Cl− ions. The equilibrium solution is obtained by integrating a set of pseudo‐transient ordinary differential equations describing the precipitation and dissolution reactions for all the possible salts to steady state. A comprehensive temperature dependent mutual deliquescence relative humidity (MDRH) parameterization is developed for all the possible salt mixtures, thereby eliminating the need for a rigorous numerical solution when ambient RH is less than MDRH(T). The solver is unconditionally stable, mass conserving, and shows robust convergence. Performance of MESA was evaluated against the Web‐based AIM Model III, which served as a benchmark for accuracy, and the EQUISOLV II solver for speed. Important differences in the convergence and thermodynamic errors in MESA and EQUISOLV II are discussed. The average ratios of speeds of MESA over EQUISOLV II ranged between 1.4 and 5.8, with minimum and maximum ratios of 0.6 and 17, respectively. Because MESA directly diagnoses MDRH, it is significantly more efficient when RH < MDRH. MESA's superior performance is partially due to its “hard‐wired” code for the present system as opposed to EQUISOLV II, which has a more generalized structure for solving any number and type of reactions at temperatures down to 190 K. These considerations suggest that MESA is highly attractive for use in 3‐D aerosol/air‐quality models for lower tropospheric applications (T > 240 K) in which both accuracy and computational efficiency are critical.
Coupled nitrogen and oxygen isotope measurements of nitrate along the eastern North Pacific margin
Authors: Sigman Daniel M. , Granger Julie , DiFiore Peter J. , Lehmann Moritz M. , Ho Ruby , Cane Greg , van Geen Alexander
Published: December 2005

Water column depth profiles along the North Pacific margin from Point Conception to the tip of Baja California indicate elevation of nitrate (NO3−) 15N/14N and 18O/16O associated with denitrification in the oxygen‐deficient thermocline waters of the eastern tropical North Pacific. The increase in δ18O is up to 3‰ greater than in δ15N, whereas our experiments with denitrifier cultures in seawater medium indicate a 1:1 increase in NO3− δ18O and δ15N during NO3− consumption. Moreover, the maximum in NO3− δ18O is somewhat shallower than the maximum in NO3− δ15N. These two observations can be summarized as an “anomaly” from the 1:1 δ18O‐to‐δ15N relationship expected from culture results. Comparison among stations and with other data indicates that this anomaly is generated locally. The anomaly has two plausible interpretations: (1) the addition of low‐δ15N NO3− to the shallow thermocline by the remineralization of newly fixed nitrogen, or (2) active cycling between NO3− and NO2− (coupled NO3− reduction and NO2− oxidation) in the suboxic zone.
Lithologic composition of the Earth's continental surfaces derived from a new digital map emphasizing riverine material transfer
Authors: Dürr Hans H. , Meybeck Michel , Dürr Stefan H.
Published: December 2005

A new digital map of the lithology of the continental surfaces is proposed in vector mode (n ≈ 8300, reaggregated at 0.5° × 0.5° resolution) for 15 rock types (plus water and ice) targeted to surficial Earth system analysis (chemical weathering, land erosion, carbon cycling, sediment formation, riverine fluxes, aquifer typology, coastal erosion). These types include acid (0.98% at global scale) and basic (5.75%) volcanics, acid (7.23%) and basic (0.20%) plutonics, Precambrian basement (11.52%) and metamorphic rocks (4.07%), consolidated siliciclastic rocks (16.28%), mixed sedimentary (7.75%), carbonates (10.40%), semi‐ to un‐consolidated sedimentary rocks (10.05%), alluvial deposits (15.48%), loess (2.62%), dunes (1.54%) and evaporites (0.12%). Where sediments, volcanics and metamorphosed rocks are too intimately mixed, a complex lithology (5.45%) class is added. Average composition is then tabulated for continents, ocean drainage basins, relief types (n = 7), 10° latitudinal bands, geological periods (n = 7), and exorheic versus endorheic domain and for formerly glaciated regions. Surficial lithology is highly heterogeneous and major differences are noted in any of these ensembles. Expected findings include the importance of alluvium and unconsolidated deposits in plains and lowlands, of Precambrian and metamorphic rocks in mid‐mountain areas, the occurrence of loess, dunes and evaporites in dry regions, and of carbonates in Europe. Less expected are the large occurrences of volcanics (74% of their outcrops) in highly dissected relief and the importance of loess in South America. Prevalence of carbonate rocks between 15°N and 65°N and of Precambrian plus metamorphics in two bands (25°S–15°N and north of 55°N) is confirmed. Asia and the Atlantic Ocean drainage basin, without Mediterranean and Black Sea, are the most representative ensembles. In cratons the influence of ancient geological periods is often masked by young sediments, while active orogens have a specific composition.
Application of secondary ion mass spectrometry to the determination of Mg/Ca in rare, delicate, or altered planktonic foraminifera: Examples from the Holocene, Paleogene, and Cretaceous
Authors: Bice Karen L. , Layne Graham D. , Dahl Kristy
Published: December 2005

Secondary ion mass spectrometry (SIMS) is useful for measuring Mg/Ca in both primary calcite and diagenetic minerals in planktonic foraminifera. The excellent spatial resolution (<10 μm) and small amount of material removed (<2 ng) makes it easy to avoid targets that include obvious embedding material and encrusting or infilling minerals such as secondary calcite and authigenic clays in diagenetically altered samples. Because analyses can be performed on individuals, SIMS is also a viable technique for generating Mg/Ca values from sediment samples in which foraminifera are rare or have low mass. For clean primary calcite samples, Mg/Ca ratios from SIMS compare well to those obtained using inductively coupled plasma mass spectrometry (ICP‐MS), while maintaining information regarding the true variability of elemental ratios within individual tests. For samples with secondary calcite or stubbornly adhering clays, SIMS enables us to accurately measure primary calcite compositions and to assess and reconcile contamination problems in bulk samples analyzed by solution‐based ICP‐MS. We have observed that SIMS is an invaluable and reliable tool for the identification and avoidance of problems of diagenesis and the analysis of rare or delicate planktonic foraminifera. However, because of operator time required to properly target delicate (thin‐walled) or contaminated planktonic foraminifera, SIMS may not be feasible for Mg/Ca studies where large numbers (hundreds) of samples must be processed and bulk measurements on multiple individuals will suffice.
User‐friendly software for vector analysis of the magnetization of long sediment cores
Authors: Mazaud A.
Published: December 2005

New software is described that is designed for easy visualization and treatment of stepwise demagnetization of the natural remanent magnetization measured along sediment cores with pass‐through magnetometers. The software displays demagnetization diagrams (Zijderveld plots) at successive horizons for any depth interval selected by the user. Paleomagnetic directions are automatically calculated using principal component analysis, with an anchored or a free origin. The demagnetization steps to be considered for the diagram visualization and paleodirection calculations are selected by the user. Maximum angular deviation angles and median destruction fields are also calculated. All the results are stored in a single data sheet, which can be easily exported. Demagnetization diagrams can be printed and copied. This Microsoft Excel software can be used by PC or Macintosh microcomputers.
Second‐order magnetic phase transition in the Earth
Authors: Kiss J. , Szarka L. , Prácser E.
Published: December 2005

It is known that second‐order magnetic phase transition, the transition between ferromagnetic (ferrimagnetic) and paramagnetic states of the material at the Curie temperature, is accompanied by a sharp (theoretically infinite) enhancement of the magnetic susceptibility. A second‐order magnetic phase transition within the Earth (usually at mid‐crustal depths, depending on geothermal conditions and on the type of magnetic material) is assumed to produce extremely high susceptibility zones of a thickness of a few hundreds of meters. Such strongly magnetized zones may be sources of well‐known but not‐yet explained geomagnetic anomalies, and at the same time, they may produce complicated electrical conductivity anomalies, as well. The second‐order magnetic phase transition should be taken into account as one of the possible sources of geomagnetic and magnetotelluric anomalies.
Scan asymmetries in AMSU‐B data
Authors: Buehler S. A. , Kuvatov M. , John V. O.
Published: December 2005

A simple method of averaging measurements for different scan positions was used to quantify scan asymmetries in AMSU‐B brightness temperatures for the sensors on the satellites NOAA 15, 16, and 17. The method works particularly well for the sounding channels 18 to 20. The asymmetries are small in most cases. In particular, asymmetries for Channel 18 are below 1.90, −0.53, and 0.49 K for NOAA 15, 16, and 17, respectively. On the other hand, it was found that the instrument on NOAA 15 has significant asymmetries for Channels 19 and 20, which seem to be related to the known radio frequency interference problem for this instrument. The use of the appropriate set of interference correction coefficients significantly reduces the asymmetry.
Alfvén wave heating of heavy ions in the expanding solar wind: Hybrid simulations
Authors: Hellinger Petr , Velli Marco , Trávníček Pavel , Gary S. Peter , Goldstein Bruce E. , Liewer Paulett C.
Published: December 2005

We present hybrid expanding box simulations of the interaction of left‐handed Alfvén waves with protons, alpha particles, and a tenuous population of oxygen O5+. The Alfvén waves are initially nonresonant with the ions, and the expansion brings them to the cyclotron resonance with O5+ ions, then with alpha particles, and finally with protons. The simulations show that O5+ ions are efficiently heated in the directions perpendicular to the background magnetic field but are only slightly accelerated. Oxygen scattering has a finite time span and saturates mainly due to the marginal stabilization with respect to the oxygen cyclotron instability generated by the temperature anisotropy. During the scattering, oxygen ions are able to absorb only a limited amount of available fluctuating energy and, for the parameters used in the simulations, their presence has a minimum influence on alpha particles and protons.
Rethinking “Yellowstone in Yukon” and Baja British Columbia: Paleomagnetism of the Late Cretaceous Swede Dome stock, northern Canadian Cordillera
Authors: McCausland P. J. A. , Symons D. T. A. , Hart C. J. R.
Published: December 2005

Paleomagnetic results obtained from the 69.8 Ma Swede Dome stock, emplaced into the pericratonic Yukon Tanana Terrane (YTT) west of Dawson, Yukon, indicate a minimal northward translation of 360 ± 575 km and a clockwise rotation of 20° ± 23° with respect to North America, in accord with the displacement of 425 km along the nearby Tintina Fault. Coeval Carmacks Group volcanics in contrast have previously indicated ∼1900 km northward translation and minimal rotation and have been proposed to be a displaced manifestation of the fixed Yellowstone hot spot, thus providing an independent estimate of the Late Cretaceous paleoposition of the “Baja British Columbia” terranes of western North America. A compilation of recent mid and Late Cretaceous paleomagnetic results from the YTT and Intermontane Belt (IMB) terranes reveals that the Carmacks Group paleomagnetic result is anomalous. The YTT and IMB terranes, which form the bulk of Baja British Columbia, appear instead to have experienced <1000 km northward translation with respect to North America since 70 Ma, consistent with geological estimates of motion along plausible accommodating faults. In addition, past mobility of the Hawaii‐Emperor hot spot implies that the Pacific hot spots may have experienced ∼1200 km of southward motion from 81 to 47 Ma. If so, then the paleoposition of the Yellowstone hot spot if it existed at 70 Ma would likely have produced the Carmacks magmatism ∼1000 km north of Yellowstone's current latitude, consistent with a “moderate” (<1000 km) post‐70 Ma northward translation of the YTT and IMB terranes to their present position in North America.
Fusion by earthquake fault friction: Stick or slip?
Authors: Fialko Yuri , Khazan Yakov
Published: December 2005

Field observations of pseudotachylites and experimental studies of high‐speed friction indicate that melting on a slipping interface may significantly affect the magnitude of shear stresses resisting slip. We investigate the effects of rock melting on the dynamic friction using theoretical models of shear heating that couple heat transfer, thermodynamics of phase transitions, and fluid mechanics. Results of laboratory experiments conducted at high (order of m/s) slip velocities but low (order of MPa) normal stresses suggest that the onset of frictional melting may give rise to substantial increases in the effective fault strength, presumably due to viscous effects. However, extrapolation of the modeling results to in situ conditions suggests that the efficiency of viscous braking is significantly reduced under high normal and shear stresses. When transient increases in the dynamic fault strength due to fusion are not sufficient to inhibit slip, decreases in the effective melt viscosity due to shear heating and melting of clasts drastically decrease the dynamic friction, resulting in a nearly complete stress drop (“thermal runaway”). The amount of energy dissipation associated with the formation of pseudotachylites is governed by the temperature dependence of melt viscosity and the average clast size in the fault gouge prior to melting. Clasts from a coarse‐grained gouge have lower chances of survival in a pseudotachylite due to a higher likelihood of nonequilibrium overheating. The maximum temperature and energy dissipation attainable on the fault surface are ultimately limited by either the rock solidus (via viscous braking, and slip arrest) or liquidus (via thermal runaway and vanishing resistance to sliding). Our modeling results indicate that the thermally activated fault strengthening and rupture arrest are unlikely to occur in most mafic protoliths but might be relevant for quartz‐rich rocks, especially at shallow (<5–7 km) depths where the driving shear stress is relatively low.
Control of interannual and longer‐term variability of stratospheric water vapor
Authors: Fueglistaler S. , Haynes P. H.
Published: December 2005

We use trajectory calculations based on 40‐year European Reanalysis (ERA‐40) data to predict the water mixing ratio of air entering the stratosphere in the tropics ([H2O]e) and thereby to examine interannual and longer‐term changes. [H2O]e is determined from the saturation mixing ratio of the coldest point during ascent from the troposphere to the stratosphere (the Lagrangian cold point). These model predictions for the time variation of [H2O]e agree very well with a broad range of measurements (Stratospheric Aerosol and Gas Experiment (SAGE) II, Halogen Occultation Experiment (HALOE), Microwave Limb Sounder (MLS), and Atmospheric Trace Molecule Spectroscopy (ATMOS)). During periods when measurements are consistent among various sensors and ERA‐40 temperatures show good agreement with radiosondes (1995–2002), the correlation between model predictions and HALOE water vapor anomalies in the tropical lower stratosphere is r = 0.81, as high as that between HALOE and SAGE II (r = 0.8). The model predictions suggest that the stratospheric quasi‐biennial oscillation, El Niño–Southern Oscillation, and possibly volcanic eruptions all play a significant role in modulating [H2O]e, leading to interannual anomalies of order 0.5 ppmv with timescales of several months to years. Although the Lagrangian calculations show substantial interannual variability of transport pathways into the stratosphere, the results show that the interannual anomalies of [H2O]e are dominated by anomalies of the zonal mean temperature rather than by transport changes or localized temperature anomalies. This reinforces the paradox of apparently increasing stratospheric water vapor concentrations alongside, if anything, slightly decreasing temperatures at the tropical tropopause. The combination of measurement uncertainties and relatively strong interannual variability with periods of several months to years, on the one hand, limits our ability to detect, attribute, and verify long‐term trends and, on the other hand, raises the question as to whether the previously published estimates of long‐term trends are too large.
Chemical composition of dust storms in Beijing and implications for the mixing of mineral aerosol with pollution aerosol on the pathway
Authors: Sun Yele , Zhuang Guoshun , Wang Ying , Zhao Xiujuan , Li Jie , Wang Zifa , An Zhisheng
Published: December 2005

Aerosol particle samples collected in spring 2002 in Beijing were analyzed to investigate the impact of transport pathways on chemical composition of Asian dust storms (DSs). The dust storms were divided into two episodes (i.e., DS I and DS II), which were transported along different pathways identified by back‐trajectory and PM10 concentrations. The transport pathway from the westerly direction could be seen as the “polluted” pathway and the north‐northwesterly direction as the relatively “less‐polluted” one. Dust storms not only delivered large amounts of mineral elements but also carried significant quantities of pollutants. The source regions and transport pathways were two vital factors affecting chemical composition of dust storms. Ca/Al could be used as elemental tracer to identify the sources of Asian dust storms owing to the difference in Ca content in different source regions. DS I of the “polluted” pathway carried more pollution elements than DS II of the “less‐polluted” one, and the pollution elements were either from dust soil (such as Zn), the mixing of dust soil with pollution aerosol on the pathway (such as As and Pb in DS I), the “pollution” dust resuspended on the pathway and Beijing local area (such as S in DS I, As and Pb in DS II), or the reactions on the surface of dust particles.
Mesospheric sulfate aerosol layer
Authors: Mills Michael J. , Toon Owen B. , Thomas Gary E.
Published: December 2005

We investigate the heretofore unstudied role of volcanic and nonvolcanic sulfur aerosols and gases in the mesosphere. Two‐dimensional microphysical calculations show that sulfur may be an important source of particles below the cold summer mesopause. Observed increases in SO2 with altitude in the upper stratosphere had previously suggested ultraviolet destruction of H2SO4, discounting its survival in the mesosphere. Laboratory measurements have now ruled out ultraviolet photolysis of H2SO4, however, and a recent proposal of visible and near‐infrared photolysis of H2SO4 explains the SO2 observations. Our calculations show that enough H2SO4 survives this weak photolysis mechanism to produce significant sulfate aerosol surface area in the mesosphere. Neutralization of H2SO4 by metals on the surfaces of meteoritic dust is modeled and affects the mesospheric aerosol negligibly. We discuss the possible implications for this new class of particles for the formation of polar mesospheric summer echoes and polar mesospheric clouds in volcanically quiescent and active periods.
A new approach to scenario analysis using simplified chemical transport models
Authors: Im H. K. , Stein M. L. , Kotamarthi V. R.
Published: December 2005

Given the computational burden of running full chemical transport models, it is highly desirable to have alternative ways to obtain fast and accurate approximations to at least some of these model outputs. We propose two methods that closely approximate the ammonia wet deposition of the Community Multiscale Air Quality (CMAQ) model, a regional‐scale three‐dimensional chemical transport model. The first method uses a greatly simplified version of CMAQ, called here “Tracer,” which requires one fortieth the processing time of CMAQ. The second method uses an extension of the Tracer model called “Multitracer.” Both methods make use of a CMAQ run under a reference emission scenario and are shown to provide good approximations to CMAQ outputs under different emission scenarios. The first fast approximation method proposed here requires a Tracer run under the new emission scenario while the second proposed approximation only requires a matrix multiplication between a precomputed matrix that approximates the transport in the model, obtained from a single Multitracer run, and the new emission. It will be shown that this method is not a simple source‐receptor approximation of the model. As an important application of the second predictor, we propose an inverse modeling method for ammonia that makes it possible to adjust emissions by a different factor for each of the 100 subregions of the spatial domain. Testing with pseudodata yields a good match between the inverse modeled emissions and the actual emissions. Estimates of emissions using actual observations in the eastern United States show a reasonable adjustment field.
The great West African Tertiary coastal uplift: Fact or fiction? A perspective from the Angolan divergent margin
Authors: Jackson M. P. A. , Hudec M. R. , Hegarty K. A.
Published: December 2005

We explore exhumation in the coastal Kwanza Basin by combining analyses of Tertiary hiatuses and apatite fission tracks. Planktonic biozones show five major hiatuses in the Oligo‐Miocene and Plio‐Pleistocene. Between gaps, Oligo‐Miocene strata accumulated under marine conditions. A marine setting refutes the idea of a massively raised coastal plateau in the mid‐Tertiary. Marine conditions continued until ∼5 Ma. Fission track data suggest three thermal events: ∼150 Ma, during rifting and volcanism; ∼100–70 Ma, during shortening and volcanism; and ∼20–10 Ma, during exhumation. Tertiary uplift was spatially highly variable. For the Kwanza Basin, we infer that Tertiary uplift on the West African margin is indeed a fact but that estimates of uplift timing and size are unreliable when extrapolated to adjoining areas. Massive uplift (2000–4000 m) of the Precambrian craton had little structural effect in the outer basin. Instead, minor uplifts on the shelf drove late Tertiary deformation on the slope.
Burnout among Canadian and Chinese employees: a cross‐cultural study
Authors: Jamal Muhammad
Published: December 2005

This study examined the relationship of job stress with overall burnout and its three dimensions (emotional exhaustion, depersonalization and lack of accomplishment) and health problems among employees in Canada (N = 535) and the People's Republic of China (N = 685). Data were collected by means of a structured questionnaire from Canadian employees in Montreal and Chinese employees in Beijing. Pearson correlation and moderated multiple regressions were used to analyze the data. Job stressors such as work overload, ambiguity, conflict and resource inadequacy, were significantly related to many dependent variables in both countries. Moderated multiple regressions only marginally supported the role of gender as a moderator of stressor‐burnout relationship. Implications of findings are discussed for cross‐cultural research.
Closing resource gaps: toward a resource‐based theory of advantageous mergers and acquisitions
Authors: Eschen Erik , Bresser Rudi KF
Published: December 2005

This paper applies resource‐based theory to explain the success or failure of resource‐driven merger and acquisition decisions. A two‐step model identifies prerequisite conditions for deriving competitive advantage and superior financial results from mergers and acquisitions designed to acquire new resources. In a first step, we analyze alternative sources of new resources such as factor markets, internal development, and cooperation, and present a framework that explains under what conditions mergers and acquisitions are an appropriate means for closing resource gaps. In a second step, we present conditions that define financially advantageous mergers and acquisition strategies. If strategically valuable and cospecialized resources of the acquiring and the acquired firms are combined, the shareholders of both the target and the acquirer can expect to appropriate rents.
Density and strength of ties in innovation networks: an analysis of multimedia and biotechnology
Authors: Gilsing Victor , Nooteboom Bart
Published: December 2005

This paper proposes modifications and extensions to the thesis of the ‘strength of weak ties’ in interfirm networks. It proceeds on the following assumptions. First, network effects depend on the industry and on whether the focus of a network is on exploration or on exploitation. Second, next to density and strength of ties one should also look at their content, for example in terms of types of knowledge and technology. Third, the analysis should take into account matters of both competence for innovation and governance of relational risk. The paper develops theoretical propositions that argue in favour of ties in exploration that are dense and strong in three out of five dimensions. Predictions are confronted with case histories of innovation in Dutch multimedia and biotechnology industries. While this does not yield a rigorous quantitative test, and results cannot be generalized, it does yield interesting refutations that yield new insights.
Optical characterization of GaN by N+ implantation into GaAs at elevated temperature
Authors: Dhara S. , Magudapathy P. , Kesavamoorthy R. , Kalavathi S. , Nair K. G. M. , Hsu G. M. , Chen L. C. , Chen K. H. , Santhakumar K. , Soga T.
Published: December 2005

Both hexagonal wurtzite and cubic zinc blend GaN phases were synthesized in GaAs by 50keV N+ implantation at 400°C and subsequent annealing at 900°C for 15min in N2 ambient. The crystallographic structural and Raman scattering studies revealed that GaN phases were grown for fluence above 2×1017cm−2. Temperature-dependent photoluminescence study showed a sharp direct band-to-band transition peak ∼3.32eV at temperature ⩽200K. The intermediate band-gap value, with respect to ∼3.4eV for hexagonal and ∼3.27eV for cubic phases of GaN, is indicative of the formation of mixed hexagonal and cubic phases.
Small gas-phase dianions produced by sputtering and gas flooding
Authors: Franzreb Klaus , Williams Peter
Published: December 2005

We have extended our previous experiment [Schauer et al., Phys. Rev. Lett. 65, 625 (1990)] where we had produced small gas-phase dianion clusters of Cn2−(n⩾7) by means of sputtering a graphite surface by Cs+ ion bombardment. Our detection sensitivity for small Cn2− could now be increased by a factor of about 50 for odd n. Nevertheless, a search for the elusive pentamer dianion of C52− was not successful. As an upper limit, the sputtered flux of C52− must be at least a factor of 5000 lower than that of C72−, provided that the lifetime of C52− is sufficiently long to allow its detection by mass spectrometry. When oxygen gas (flooding with either O2 or with N2O) was supplied to the Cs+-bombarded graphite surface, small dianions of OCn2−(5⩽n⩽14) and O2C72− were observed in addition to Cn2−(n⩾7). Similarly, Cs+ sputtering of graphite with simultaneous SF6 gas flooding produced SCn2−(6⩽n⩽18). Mixed nitrogen-carbon or fluorine-carbon dianion clusters could not be observed by these means. Attempts to detect mixed metal-fluoride dianions for SF6 gas flooding of various Cs+-bombarded metal surfaces were successful for the case of Zr, where metastable ZrF62− was observed. Cs+ bombardment of a silicon carbide (SiC) wafer produced SiCn2− (n=6,8,10). When oxygen gas was supplied to the Cs+-bombarded SiC surface, small dianions of SiOCn2− (n=4,6,8) and of SiO2Cn2− (n=4,6) as well as a heavier unidentified dianion (at m∕z=98.5) were observed. For toluene (C7H8) vapor flooding of a Cs+-bombarded graphite surface, several hydrocarbon dianion clusters of CnHm2−(n⩾7) were produced in addition to Cn2−(n⩾7), while smaller CnHm2− with n⩽6 could not be observed. BeCn2− (n=4,6,8,10), Be2C62−, as well as BeC8Hm2− (with m=2 and/or m=1) were observed for toluene vapor flooding of a Cs+-bombarded beryllium metal foil. The metastable pentamer Be9C42−12 at m∕z=28.5 was the smallest and lightest dianion molecule that we could detect. The small dianion clusters of SCn2−, OCn2−, BeCn2−, and SiOmCn2− (m=0,1,2) have different abundance patterns. A resemblance exists between the abundance patterns of BeCn2− and SiCn2−, even though calculated molecular structures of BeC62− and SiC62− are different. The abundance pattern of SCn2− is fairly similar to that of Cn2−.
Determination of the excited-state structure of 7-azaindole-water cluster using a Franck-Condon analysis
Authors: Brause Robert , Krügler Daniel , Schmitt Michael , Kleinermanns Karl , Nakajima Atsushi , Miller Terry A.
Published: December 2005

The change of the 7-azaindole-water cluster structure upon electronic excitation was determined by a Franck-Condon analysis of the intensities in the fluorescence emission spectra obtained via excitation of five different vibronic bands. A total of 105 emission band intensities were fitted, together with the changes of rotational constants of one isotopomer. These rotational constants have been obtained from a fit to the rovibronic contour of the cluster. The geometry change upon electronic excitation to the ππ* state can be described by a strong and asymmetric shortening of the hydrogen bonds and a deformation of both the pyridine and the pyrrole rings of 7-azaindole. The resulting geometry changes are interpreted on the basis of ab initio calculations.
Adsorption structures of benzene on a Si(5512)-2×1 surface: A combined scanning tunneling microscopy and theoretical study
Authors: Hahn J. R. , Jeong Hojin , Jeong Sukmin
Published: December 2005

In the first ever attempt to study the adsorption of organic molecules on high-index Si surfaces, we investigated the adsorption of benzene on Si(5512)-(2×1) by using variable-low-temperature scanning tunneling microscopy and density-functional theory (DFT) calculations. Several distinct adsorption structures of the benzene molecule were found. In one structure, the benzene molecule binds to two adatoms between the dimers of D3 and D2 units in a tilted butterfly configuration. This structure is produced by the formation of di-σ bonds with the substrate and of two CC double bonds in the benzene molecule. In another structure, the molecule adsorbs on honeycomb chains with a low adsorption energy because of strain effects. Our DFT calculations predict that the adsorption energies of benzene are 1.03–1.20eV on the adatoms and 0.22eV on the honeycomb chains.
Reconsideration of second-harmonic generation from isotropic liquid interface: Broken Kleinman symmetry of neat air/water interface from dipolar contribution
Authors: Zhang Wen-kai , Zheng De-sheng , Xu Yan-yan , Bian Hong-tao , Guo Yuan , Wang Hong-fei
Published: December 2005

It has been generally accepted that there are significant quadrupolar and bulk contributions to the second-harmonic generation (SHG) reflected from the neat air/water interface, as well as common liquid interfaces. Because there has been no general methodology to determine the quadrupolar and bulk contributions to the SHG signal from a liquid interface, this conclusion was reached based on the following two experimental phenomena: the breaking of the macroscopic Kleinman symmetry and the significant temperature dependence of the SHG signal from the neat air/water interface. However, because the sum frequency generation vibrational spectroscopy (SFG-VS) measurement of the neat air/water interface observed no apparent temperature dependence, the temperature dependence in the SHG measurement has been reexamined and proven to be an experimental artifact. Here we present a complete microscopic analysis of the susceptibility tensors of the air/water interface, and show that dipolar contribution alone can be used to address the issue of the breaking of the macroscopic Kleinman symmetry at the neat air/water interface. Using this analysis, the orientation of the water molecules at the interface can be obtained, and it is consistent with the measurement from SFG-VS. Therefore, the key rationales to conclude significantly quadrupolar and bulk contributions to the SHG signal of the neat air/water interface can no longer be considered as valid as before. This new understanding of the air/water interface can shed light on our understanding of the nonlinear optical responses from other molecular interfaces as well.
Damped and thermal motion of laser-aligned hydrated macromolecule beams for diffraction
Authors: Starodub D. , Doak R. B. , Schmidt K. , Weierstall U. , Wu J. S. , Spence J. C. H. , Howells M. , Marcus M. , Shapiro D. , Barty A. , Chapman H. N.
Published: December 2005

We consider a monodispersed Rayleigh droplet beam of water droplets doped with proteins. An intense infrared laser is used to align these droplets. The arrangement has been proposed for electron- and x-ray-diffraction studies of proteins which are difficult to crystallize. This paper considers the effect of thermal fluctuations on the angular spread of alignment in thermal equilibrium, and relaxation phenomena, particularly the damping of oscillations excited as the molecules enter the field. The possibility of adiabatic alignment is also considered. We find that damping times in a high-pressure gas cell as used in x-ray-diffraction experiments are short compared with the time taken for molecules to traverse the beam and that a suitably shaped field might be used for electron-diffraction experiments in vacuum to provide adiabatic alignment, thus obviating the need for a damping gas cell.
Effective electrostatic interactions in solutions of polyelectrolyte stars with rigid rodlike arms
Authors: Wang Hao , Denton Alan R.
Published: December 2005

In solutions of star-branched polyelectrolytes, electrostatic interactions between charged arms on neighboring stars can compete with intrastar interactions and rotational entropy to induce anisotropy in the orientational distribution of arms. We explore the influence of arm orientational anisotropy on effective star-star interactions for model stars comprising rigid rodlike arms with evenly spaced charged monomers interacting via an effective screened-Coulomb (Yukawa) potential. Monte Carlo simulation and density-functional theory are used to compute the arm orientational distributions and effective pair potentials between weakly charged stars. For comparison, a torque balance analysis is performed to obtain the configuration and energy of the ground state, in which the torque vanishes on each arm of the two-star system. The degree of anisotropy is found to increase with the strength of electrostatic interactions and proximity of the stars. As two stars begin to overlap, the forward arms are pushed back by interstar arm-arm repulsion, but partially interdigitate due to rotational entropy. At center-center separations approaching complete overlap, the arms relax to an isotropic distribution. For nonoverlapping stars, anisotropy-induced changes in the intra- and interstar arm-arm interactions largely cancel and the effective pair interactions are then well approximated by a simple Yukawa potential, as predicted by linear-response theory for a continuum model of isotropic stars [A. R. Denton, Phys. Rev. E 67, 11804 (2003)]. For overlapping stars, the effective pair interactions in the simple rigid-arm-Yukawa model agree closely with simulations of a molecular model that includes flexible arms and explicit counterions [A. Jusufi et al., Phys. Rev. Lett. 88, 018301 (2002); J. Chem. Phys. 116, 11011 (2002)].