bluuebunny/crossref_metadata_2025 huggingface dataset:
Sekundäre Hydroxyalkylphosphane: Synthese und Charakterisierung mono‐, bis‐ und trisalkoxyphosphan‐substituierter Zirconiumkomplexe und des heterobimetallischen Dreikernkomplexes [Cp2Zr{O(CH2)3PHMes(AuCl)}2]
Authors: Sterzik Anke , Lönnecke Peter , Hey‐Hawkins Evamarie
Published: August 2005

Secondary Hydroxyalkylphosphanes: Synthesis and Characterization of Mono‐, Bis‐ and Trisalkoxyphosphane‐substituted Zirconium Complexes and the Heterobimetallic Trinuclear Complex [Cp2Zr{O(CH2)3PHMes(AuCl)}2]

The secondary hydroxyalkylphosphanes RPHCH2OH [R = 2,4,6‐Me3C6H2 (Mes) (1), 2,4,6‐iPr3C6H2 (Tipp) (2)], 1‐AdPH‐2‐OH‐cyclo‐C6H10 (3) and RPH(CH2)3OH [R = Ph (4), Mes (5), Tipp (6), Cy (7), tBu (8)] were obtained from primary phosphanes RPH2 and formaldehyde (1, 2) or from LiPHR and cyclohexene oxide (3) or trimethylene oxide (4‐8). Starting from 5 or 7 and [CpR2ZrMe2] [CpR = C5EtMe4 (Cp°), C5H5 (Cp), C5MeH4 (Cp′)], the monoalkoxyphosphane‐substituted zirconocene complexes [CpR2Zr(Me){O(CH2)3PHMes}] [CpR = Cp° (9), Cp (10)] were prepared. With [CpR2ZrCl2], the bisalkoxyphosphane‐substituted complexes [Cp′2Zr{O(CH2)3PHMes}2] (11) and [Cp2Zr{O(CH2)3PHCy}2] (12) are obtained, and with [TpRZrCl3], the trisalkoxyphosphane‐substituted zirconium complexes [TpRZr{O(CH2)3PHMes}3] [TpR = trispyrazolylborato (Tp) (13), TpR = tris(3,5‐dimethyl)pyrazolylborato (Tp*) (14)] are prepared.

The reaction of 5 with [AuCl(tht)] (tht = tetrahydrothiophene) yielded the mononuclear complex [AuCl{PHMes(CH2)3OH}] (15). The trinuclear complex [Cp2Zr{O(CH2)3PHMes(AuCl)}2] (16) was obtained from [Cp2ZrCl2] and 15. Compounds 1‐16 were characterized spectroscopically (1H‐, 31P‐, 13C‐NMR; IR; MS) and compound 2 also by crystal structure determination. The bis‐ and trisalkoxyphosphane‐substituted complexes 11‐14 and 16 were obtained as mixtures of two diastereomers which could not be separated.
Synthesis and Crystal Structure of CsCu3O2, Containing a New Type of Oxocuprate(I) Polyanion (Z. Anorg. Allg. Chem. (2003), 629, 2435)
Authors: Sofin M. , Peters E. M. , Jansen M.
Published: August 2005

The d‐values originally given in Table 3 are in error by a factor of 2.17. For the correct powder data, see Table 3 below.
Hematocrit and blood chemistry values in three genera of captive hornbills
Authors: Villegas A. , Corbacho C. , Sánchez‐Guzmán J.M. , Corbacho P. , Morán R.
Published: August 2005

This study reports hematocrit and blood chemistry values for captive adult individuals belonging to three genera of hornbills (Bucerotidae), Aceros, Anthracoceros, and Ceratogymna, and evaluates genera and gender specific differences in these values. Ceratogymna differs significantly from the other two genera in the concentration of total proteins, cholesterol, triglycerides, phosphorus, potassium, and sodium. Blood glucose concentrations in Aceros were lower than those in the other two genera. Plasma levels of enzymes differed between Aceros and Ceratogymna. With respect to gender differences, Aceros males had greater plasma levels of alanine aminotransferase (ALT), calcium and phosphorus than did the females, and the Ceratogymna males had higher concentrations of triglycerides. Body mass was correlated with hematocrit, cholesterol, total proteins, and urea in Aceros and with calcium concentration in Ceratogymna. These results are the first data available on reference ranges of blood values in individuals of this family of birds and may therefore be very useful as a complementary diagnostic tool in the veterinary care of individuals of these species in captivity. Zoo Biol 0:1–9, 2005. © 2005 Wiley‐Liss, Inc.
Management Strategies, Early Results, Benefits, and Risk Factors of Laparoscopic Repair of Perforated Peptic Ulcer
Authors: Lunevicius Raimundas , Morkevicius Matas
Published: August 2005

The primary goal of this study was to describe epidemiology and management strategies of the perforated duodenal ulcer, as well as the most common methods of laparoscopic perforated duodenal ulcer repair. The secondary goal was to demonstrate the value of prospective and retrospective studies regarding the early results of surgery and the risk factors. The tertiary goal was to emphasize the benefits of this operation, and the fourth goal was to clarify the possible risk factors associated with laparoscopic repair of the duodenal ulcer. The Medline/Pubmed database was used. Review was done after evaluation of 96 retrieved full‐text articles. Thirteen prospective and twelve retrospective studies were selected, grouped, and summarized. The spectrum of the retrospective studies’ results are as follows: median overall morbidity rate 10.5 %, median conversion rate 7%, median hospital stay 7 days, and median postoperative mortality rate 0%. The following is the spectrum of results of the prospective studies: median overall morbidity rate was slightly less (6%); the median conversion rate was higher (15%); the median hospital stay was shorter (5 days) and the postoperative mortality was higher (3%). The risk factors identified were the same. Shock, delayed presentation (> 24 hours), confounding medical condition, age > 70 years, poor laparoscopic expertise, ASA III‐IV, and Boey score should be considered preoperative laparoscopic repair risk factors. Each of these factors independently should qualify as a criterion for open repair due to higher intraoperative risks as well as postoperative morbidity. Inadequate ulcer localization, large perforation size (defined by some as > 6 mm diameter, and by others as > 10 mm), and ulcers with friable edges are also considered as conversion risk factors.
How are Volume–Outcome Associations Related to Models of Health Care Funding and Delivery? A Comparison of the United States and Canada
Authors: Urbach David R. , Croxford Ruth , MacCallum Nancy L. , Stukel Thérèse A
Published: August 2005

How models of health care financing and delivery affect patterns of procedure volumes, outcomes, and volume–outcome associations is not known. We compared volume–outcome studies done in Canada, which provides residents with universal, single‐payer health care, with those done in the United States, to determine whether there was a difference in the likelihood of finding statistically significant volume–outcome associations. We analyzed 142 articles, most (90.1%) of which were from the United States. The articles described a total of 291 separate analyses. After adjusting for the clustering of multiple analyses in the same study, the likelihood of finding a statistically significant volume–outcome association was substantially lower in Canadian studies as compared with those from the United States (odds ratio 0.24, 95% confidence interval 0.08 to 0.74, p = 0.01). This result persisted after adjustment for the procedure/condition studied, and the number of study subjects. Canadian volume–outcome analyses are less likely to identify statistically significant volume–outcome associations than US studies, possibly because of the smaller size of some Canadian studies. It is also possible that different models of health care financing and delivery affect patterns of procedure volumes and volume–outcome associations. By promoting competition between hospitals and providers, market‐based models may exacerbate existing variations in the quality of hospital care.
Drugs from Emasculated Hormones: The Principle of Syntopic Antagonism
Authors: Black James
Published: August 2005

This lecture outlines the early stages in the discovery of adrenaline β-receptor antagonists and of the histamine H2-receptor antagonists. It ends with a brief personal view about future research.
The Photosynthetic Reaction Centre from the Purple Bacterium Rhodopseudomonas
viridis
Authors: Deisenhofer Johann , Michel Harmut
Published: August 2005

We first describe the history and methods of membrane protein crystallization, and show how the structure of the photosynthetic reaction centre from the purple bacterium Rhodopseudomonas viridis was solved. The structure of this membrane protein complex is correlated with its function as a light-driven electron pump across the photosynthetic membrane. Finally we draw conclusions on the structure of the photosystem II reaction centre from plants and discuss the aspects of membrane protein structure.
The Molecular Biology of Memory Storage: A Dialog Between Genes and Synapses
Authors: Kandel Eric R.
Published: August 2005

The biology of learning, and short-term and long-term memory, as revealed by Aplysia and other organisms, is reviewed.
Yeast and Cancer
Authors: Hartwell Leland H.
Published: August 2005

The discovery of genes that control cell division in yeast, and their relation to cancer, is reviewed.
The implications of warming climate for the management of North Sea demersal fisheries
Authors: Cook R.M. , Heath M.R.
Published: August 2005

Since the 1950s, records from the North Sea show a gradual increase in temperature. Using temperature as a proxy indexing the state of the environment, relationships between recruitment, spawning-stock biomass, and temperature are investigated for major North Sea stocks. Cod, plaice, and sole exhibit significant negative relationships between temperature and recruitment, while there is evidence of a positive effect for saithe and whiting. Stock-recruitment models that incorporate temperature are developed and used to examine implications for the management of these stocks with small increases in mean winter sea surface temperature. These suggest that for cod, minimum safe biomass reference points are unlikely to be achieved even at fishing mortality rates that are considered safe. The same analysis suggests that sustainable fishing for cod is still possible with higher yields than have been experienced in recent years.
Implications of climate change for the management of North Sea cod (Gadus morhua)
Authors: Kell Laurence T. , Pilling Graham M. , O'Brien Carl M.
Published: August 2005

Robustness of both short-term stock biomass recovery and longer-term sustainable management strategies to different plausible climatic change scenarios were evaluated for North Sea cod (Gadus morhua), where climate was assumed to impact growth and recruitment. In the short term, climate change had little effect on stock recovery, which depends instead upon reducing fishing effort to allow existing year classes to survive to maturity. In the longer term, climate change has greater effects on stock status, but higher yields and biomass can be expected if fishing mortality is reduced. Incorporating environmental covariates in stock assessment predictions will not achieve sustainable resource use. The implications of climate change for biological reference points depend upon the mechanism through which temperature acts on recruitment, i.e. on juvenile survival or carrying capacity. It is not possible to distinguish between these processes with stock assessment data sets alone. However, this study indicates that reference points based on fishing mortality appear more robust to uncertainty than those based on biomass. Ideally, simpler management procedures are required that meet pre-agreed management objectives and are robust to uncertainty about the true dynamics.
Complex Regional Pain Syndrome Type 1 after Fractures of the Distal Radius: A Prospective Study of the Role of Psychological Factors
Authors: PUCHALSKI P. , ZYLUK A.
Published: August 2005

A prospective study was designed to investigate the question “Do patients who develop Complex Regional Pain Syndrome Type 1 (CRPS Type 1) after fracture of the distal radius display different psychological behaviour patterns and/or are more depressive than those who recover uneventfully after this fracture?” Sixty-two patients of mean age 56 years with displaced distal radius fractures were operated on by closed reduction and percutaneous fixation with K-wires. All these patients were examined psychologically on the day after the operation. A series of standardized, self-administered questionnaires was used to assess personality and depression. Fifty of the 62 patients were reassessed at 2 months for symptoms and signs of CRPS Type 1 and a diagnosis of this condition made on clinical grounds. Nine patients (18%) were diagnosed as having CRPS Type 1. There were no significant differences in scores on any of the personality and depression scales between CRPS Type 1 and non-CRPS Type 1 patients. Therefore, patients who eventually developed CRPS Type 1 after radial forearm fracture had neither a unique psychological pattern nor displayed more symptoms of depression than those who recovered uneventfully.
Weakening Ties with the Ancestral Homeland in China: The Case Studies of Contemporary Singapore and Malaysian Chinese
Authors: HOE YOW CHEUN
Published: August 2005

In the last two decades there has been much scholarly and journalistic attention given to the issue of how Chinese overseas relate themselves to China. This happened against a backdrop of two major developments in Asia. The first has to do with the fact that many ethnic Chinese outside mainland China have been faring well economically and accumulating considerable wealth in Singapore, Malaysia, Indonesia, Thailand, Hong Kong, and Taiwan in the second half of the twentieth century. The second is the rise of China as an economic superpower attracting foreign capital after it reopened itself and launched economic reform in 1978.
What's Become of the Pandit? Rethinking the History of Sanskrit Scholars in Colonial Bengal
Authors: HATCHER BRIAN A.
Published: August 2005

This essay raises a single question for which it ventures two kinds of answers, one historical and the other historiographical. On the one hand, to ask ‘What's become of the pandit?’ is to express an interest in finding out about transformations over time in the activities, experiences, and social placement of pandits—for present purposes in the context of colonial Bengal. Taken in this sense, the question reflects a desire to examine the diverse experiences of Sanskrit pandits, perhaps to inquire about the degree to which they either may or may not be illustrative of other sorts of changes taking place in colonial Indian society. On the other hand, to ask ‘What's become of the pandit?’ is to suggest that it may be worth investigating what we mean by the word ‘pandit’ and how we have come to view pandits as we do. What we're asking thus is really, ‘What's become of the pandit in modern scholarly discourse?’ In this sense, the question is a historiographical or methodological one. It suggests there may be important reasons why scholars tend to conceptualize the life and work of pandits as they do, and reminds us that becoming aware of these reasons might allow us to gain a better perspective on our own field of study.
The Transformation of an Overseas Chinese Family—Three Generations of the Eu Tong Sen Family, 1822–1941
Authors: CHUNG STEPHANIE PO-YIN
Published: August 2005

Architecture can be viewed as a reflection of value placed on life. In colonial Hong Kong, a distinctive Gothic-style castle, Euston, was built by tycoon Eu Tong Sen (1877–1941) as his family's grand residence. Eu was a prominent figure in South China and Southeast Asia and remains a local legend decades after his death. Eu's castle, being built in 1928 and demolished in the 1980s, was and still is one of the most recognizable monuments in the region. Although Eu did not leave behind any autobiography or memoirs, the monumental castle can be regarded as a symbolic manifestation of his life story. The design of the castle is of mixed ancestry—it is a reconciliation of traditional Chinese design based on feng shui (Chinese geomancy) with European architectural elements. The fusion of East-West architectural building elements, as symbolized by the Eu castle, was a significant achievement symbolizing general social and cultural changes spanning more than a century.
Experiencing the past? The development of a phenomenological archaeology in British prehistory
Authors: Brück Joanna
Published: August 2005

In recent years the development of a phenomenological archaeology has provoked considerable discussion within the discipline, particularly within British prehistory. This paper provides a review of this challenging body of research, outlining its problems and potentials and setting it within its broader disciplinary context. Phenomenology has been used to great effect to critique the Cartesian rationalism inherent in traditional archaeological approaches, encouraging imaginative and valuable reinterpretations of the architecture and landscape settings of different monuments. Nonetheless, there are a number of significant problems raised by this work. The suggestion that the archaeologist’s embodied engagement with an ancient monument or landscape can provide an insight into past experiences and interpretations is critically considered. The epistemological status of the knowledge-claims made, including how and whether the patterns identified should be verified, is discussed. The contribution of phenomenology to postprocessual debates surrounding concepts of the self, the individual, embodiment and emotion are also explored. The work of key proponents of phenomenology such as Tilley and Thomas provides a particular focus, although a range of other authors are also considered.
The circulation of coins and the Roman periphery
Authors: Şaul Mahir
Published: August 2005

The discussion of coin finds in the European periphery and the light they throw on the nature of the Roman socio-economic complex is the most interesting part of this paper for me, because it is somewhat analogous to the relations of western Europe with west Africa in the 19th and early colonial 20th centuries. But this commentary steps over into the vast field of classical archaeology that is unfamiliar to me and instead of pursuing this analogy I find it more comfortable to make a few more general remarks on the use of social anthropological ideas and questions of method.
From monetization to culture change
Authors: Scheidel Walter
Published: August 2005

Aarts's argument revolves around three binaries: formalist and substantivist approaches to the study of the ancient economy, narrow economy-centered and broader culture-centered assessments of money use, and long-term and short-term transactional orders. Binary opposites play a critical role in our construction of the world, and consequently provide potent rhetorical tools for structuring an argument and especially for demarcating the novel and imaginative from the old and staid. At the same time, while this arrangement helps to define ideal types, it also runs the risk of obscuring what the debate is really about.
Sufficient Sample Sizes for Multilevel Modeling
Authors: Maas Cora J. M. , Hox Joop J.
Published: August 2005

Abstract. An important problem in multilevel modeling is what constitutes a sufficient sample size for accurate estimation. In multilevel analysis, the major restriction is often the higher-level sample size. In this paper, a simulation study is used to determine the influence of different sample sizes at the group level on the accuracy of the estimates (regression coefficients and variances) and their standard errors. In addition, the influence of other factors, such as the lowest-level sample size and different variance distributions between the levels (different intraclass correlations), is examined. The results show that only a small sample size at level two (meaning a sample of 50 or less) leads to biased estimates of the second-level standard errors. In all of the other simulated conditions the estimates of the regression coefficients, the variance components, and the standard errors are unbiased and accurate.
A Green's function for the excitation of torsional oscillations in the Earth's core
Authors: Buffett B. A. , Mound J. E.
Published: August 2005

Convection in the Earth's outer core excites torsional oscillations in the fluid, which couple to rigid‐body motion of the inner core and mantle. The torsional oscillations are detected as time variations of the magnetic field, whereas the motion of the mantle is observed as changes in the length of day. We develop a model for the motion of the core‐mantle system using a Green's function for the impulse response to a localized source of excitation. The response to a source which is distributed in both space and time is obtained by convolving the Green's function with the appropriate source function. The Green's function is constructed by summing the normal modes of the system. We derive an orthogonality condition for the normal modes and use it to determine the coefficients of the normal mode expansion. Examples of the Green's function are presented for a variety of source locations. The predictions may be compared with observations to provide insights into the convective processes that excite the oscillations. It may also be possible to recover the physical properties that determine the period of the normal modes, including the structure of the magnetic field inside the outer core and the nature of coupling at the fluid boundaries. We outline a strategy for inverting the observations and identify potential difficulties due to the nonuniqueness of the inverse problem.
Dissolved silicate in coastal marine rainwaters: Comparison between the Yellow Sea and the East China Sea on the impact and potential link with primary production
Authors: Zhang J. , Zhang G. S. , Liu S. M.
Published: August 2005

Rainwater samples are collected from islands and seagoing cruises in the Yellow Sea and the East China Sea to determine concentration and to estimate deposition flux for dissolved silicate (DSi), together with other nutrients (e.g., nitrogen) by spectrophotometry. Concentrations of dissolved silicate in rainwater show considerable variation in time and space, with 0.5–15 μM at the Yellow Sea and the East China Sea. The (NO3− + NH4+)/DSi ratio in rainwater changes over up to 2 orders of magnitude, with high levels in winter and low in autumn. Levels of DSi falls with higher rainfall, and a positive relationship can be established with amount of total particles in rainwater samples. The deposition of DSi via rainfall is 0.97 × 109 mol yr−1 for the Yellow Sea and 2.0 × 109 mol yr−1 for the East China Sea, respectively, 20–40% higher than the atmospheric dry deposition estimated by previous work but shows critical importance to the marine ecosystems at low trophic level in terms of comparison of chemical budget and new production. The extrapolation to the global ocean indicates that aeolian inputs (i.e., wet and dry depositions) of dissolved silicate can be on the order of 0.9 × 1012 mol yr−1, with ∼20% of this amount is distributed in the continental margin.
Reconstruction of paleo–particulate organic carbon fluxes for the Campbell Plateau region of southern New Zealand using the zinc content of sponge spicules
Authors: Ellwood Michael J. , Kelly Michelle , Neil Helen , Nodder Scott D.
Published: August 2005

The zinc concentration of siliceous sponge spicules was determined from spicules recovered from four sediment cores spanning the last 160 kyr, from the Campbell Plateau region southeast of New Zealand. Zinc/Si results showed little difference between Holocene and glacial aged spicules. An increase in Zn/Si was observed for core Y14, where Zn/Si peaked at about 0.6 μmol/mol during marine isotope stages 5a–5b. To better understand the role carbon export has on sponge Zn/Si, we explored the strong relationship observed between surficial sediment particulate organic carbon (POC) and the Zn/Si of sponge silica and related this to sediment trap POC flux estimates. Conversion of the Zn/Si records to benthic POC fluxes suggests that there has been little change in the amount of POC reaching Campbell Plateau sediments over the past 30 kyr. These results suggest that surface productivity over the Campbell Plateau has remained relatively low over the past 160 kyr and suggests that glacial productivity was not significantly higher than the present day. Finally, this work reveals that living marine sponges appear to act as the biological equivalents of moored sediment traps, recording the flux of POC to the seafloor by archiving zinc associated with sinking POC in the growing silica skeleton.
A hierarchical family of three-dimensional potential energy surfaces for He-CO
Authors: Peterson Kirk A. , McBane George C.
Published: August 2005

A hierarchical family of five three-dimensional potential energy surfaces has been developed for the benchmark He-CO system. Four surfaces were obtained at the coupled cluster singles and doubles level of theory with a perturbational estimate of triple excitations, CCSD(T), and range in quality from the doubly augmented double-zeta basis set to the complete basis set (CBS) limit. The fifth corresponds to an approximate CCSDT/CBS surface (CCSD with iterative triples/CBS, denoted CBS+corr). The CBS limit results were obtained by pointwise basis set extrapolations of the individual counterpoise-corrected interaction energies. For each surface, over 1000 interaction energies were accurately interpolated using a reproducing kernel Hilbert space approach with an R−6+R−7 asymptotic form. In each case, both three-dimensional and effective two-dimensional surfaces were developed. In standard Jacobi coordinates, the final CBS+corr surface has a global minimum at rCO=2.1322a0,R=6.418a0, and γ=70.84° with a well depth of −22.34cm−1. The other four surfaces have well depths ranging from −14.83cm−1 [CCSD(T)/d-aug-cc-pVDZ] to −22.02cm−1 [CCSD(T)/CBS]. For each of these surfaces the infrared spectrum has been accurately calculated and compared to experiment, as well as to previous theoretical and empirical surfaces. The final CBS+corr surface exhibits root-mean-square and maximum errors compared to experiment (He4) of just 0.03 and 0.04cm−1, respectively, for all 42 transitions and is the most accurate ab initio surface to date for this system. Other quantities investigated include the interaction second virial coefficient, the integral cross sections, and thermal rate coefficients for rotational relaxation of CO by He, and rate coefficients for CO vibrational relaxation by He. All the observable quantities showed a smooth convergence with respect to the quality of the underlying interaction surface.
The effects of supramolecular assembly on exciton decay rates in organic semiconductors
Authors: Daniel Clément , Makereel François , Herz Laura M. , Hoeben Freek J. M. , Jonkheijm Pascal , Schenning Albertus P. H. J. , Meijer E. W. , Friend Richard H. , Silva Carlos
Published: August 2005

We present time-resolved photoluminescence measurements on two series of oligo-p-phenylenevinylene (OPV) materials that are functionalized with quadruple hydrogen-bonding groups. These form supramolecular assemblies with thermotropic reversibility. The morphology of the assemblies depends on the way that the oligomers are functionalized; monofunctionalized OPVs (MOPVs) form chiral, helical stacks while bifunctionalized OPVs (BOPVs) form less organized structures. These are therefore model systems to investigate the effects of supramolecular assembly, the effects of morphology, and the dependence of oligomer length on the radiative and nonradiative rates of π-conjugated materials. The purpose of this work is to use MOPV and BOPV derivatives as model systems to study the effect of intermolecular interactions on the molecular photophysics by comparing optical properties in the dissolved phase and the supramolecular assemblies. A simple photophysical analysis allows us to extract the intrinsic radiative and nonradiative decay rates and to unravel the consequences of interchromophore coupling with unprecedented detail. We find that interchromophore coupling strongly reduces both radiative and intrinsic nonradiative rates and that the effect is more pronounced in short oligomers.
Adsorbate motions induced by inelastic-tunneling current: Theoretical scenarios of two-electron processes
Authors: Ueba H. , Mii T. , Lorente N. , Persson B. N. J.
Published: August 2005

We discuss how the excitation of high-frequency modes in adsorbed molecules may result in motion (e.g., rotation, translation, or dissociation) of the molecules. Our study is based on rate equations and considers one- and two-vibrational excitation processes, corresponding to linear and quadratic dependences of the reaction rate on the tunneling current in the case the scanning tunneling microscopy is used to excite the vibrations (inelastic tunneling). From the results reported in this paper it should be possible to obtain intramolecular transition rates directly from the experimental data, and gain some understanding on how these important quantities depend on the modes involved and on the substrate.
Periodic sedimentation of three particles in periodic boundary conditions
Authors: Ekiel-Jeżewska M. L. , Felderhof B. U.
Published: August 2005

Solutions of the equations of Stokesian dynamics for point particles are found for periodic boundary conditions with three particles per unit cell of a simple cubic lattice. Two particles per cell move with equal velocity, but three particles per cell usually lead to irregular motion. For a class of initial conditions with special symmetry motions are found that are periodic in time as well as in space. It is shown that there is a range of stability in which the motions are robust under perturbation.
Dissolution nature of the lithium hydroxide by water molecules
Authors: Veerman Anupriya , Lee Han Myoung , Kim Kwang S.
Published: August 2005

The structures, stabilities, thermodynamic quantities, dissociation energies, infrared spectra, and electronic properties of LiOH hydrated by up to seven water molecules are investigated by using the density-functional theory and the Møller-Plesset second-order perturbation theory (MP2). Further accurate analysis based on the coupled-cluster theory with singles, doubles, and perturbative triples excitations agrees with the MP2 results. The Li–OH stretch mode significantly shifts with the increase of water molecules, and it eventually disappears upon dissociation. It is revealed that seven water molecules are needed for the stable dissociation of LiOH (as a completely dissociated conformation), in contrast to the cases of RbOH and CsOH which require four and three water molecules, respectively.
Shell buckling of individual multiwalled carbon nanotubes using nanoindentation
Authors: Waters J. F. , Guduru P. R. , Jouzi M. , Xu J. M. , Hanlon T. , Suresh S.
Published: August 2005

Although the mechanical behavior of carbon nanotubes has been studied extensively in recent years, very few experimental results exist on the shell buckling of nanotubes, despite its fundamental importance in nanotube mechanics and applications. Here we report an experimental technique in which individual multiwalled carbon nanotubes were axially compressed using a nanoindenter and the critical shell-buckling load was measured. The results are compared with predictions of existing continuum theories, which model multiwalled carbon nanotubes as a collection of single-walled shells, interacting through van der Waals forces. The theoretical models significantly underpredict the experimental buckling load.
Accurate prediction for electron affinities of the radicals derived from the halide benzene
Authors: Xu Wenguo , Gao Aifang
Published: August 2005

The molecular structures and electron affinities of eight radicals derived from the halide benzene by removing a hydrogen atom have been determined using seven hybrid Hartree-Fock/density-functional methods. The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted as DZP++. These methods have been carefully calibrated [J. C. Rienstra-Kiracofe, G. S. Tschumper, H. F. Schaefer, S. Nandi, and G. B. Ellison, Chem. Rev. (Washington, D. C.) 102, 231 (2002)]. The geometries are fully optimized with each density-functional theory method and discussed, respectively. The three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity, the vertical electron affinity, and the vertical detachment energy. The most reliable adiabatic electron affinities (with zero-point vibrational energy correction), obtained at the DZP++ B3LYP level of theory, are 1.74 eV (o-C6H4F∙), 1.39 eV (m-C6H4F∙), 1.34 eV (p-C6H4F∙), 1.78 eV (o-C6H4Cl∙), 1.53 eV (m-C6H4Cl∙), 1.45 eV (p-C6H4Cl∙), 2.06 eV (o-C6H3F2∙), and 2.04 eV (p-C6H3F2∙), respectively. Compared with the experimental values, the average absolute error of the B3LYP method is 0.03 eV. The BLYP, BP86, and BPW91 functionals also gave excellent predictions, with average absolute errors of 0.05, 0.08, and 0.08 eV, respectively.
Receptivity of a boundary-layer flow to a three-dimensional hump at finite Reynolds numbers
Authors: Tumin Anatoli , Reshotko Eli
Published: August 2005

The receptivity of boundary-layer flow to a three-dimensional hump (an array of humps) at a finite Reynolds number is solved with the help of an expansion of the linearized solution of Navier-Stokes equations into the biorthogonal eigenfunction system. There are two counterrotating vortices behind the roughness element that bring the high-speed fluid down into the wake region. Depending on the geometry, two relatively high-speed streaks could be observed in the wake downstream from the hump. The results for the flow-field structure are in qualitative agreement with available computational data. The quantitative discrepancy is attributed to the nonlinear character of the receptivity mechanism at the parameters considered in the computational studies.
Analyses of a slender body moving near a curved ground
Authors: Wang Q. X.
Published: August 2005

The irrotational flow induced by a slender body moving near a curved ground is analyzed by extending the classical slender body theory. The flow far away from the body is shown to be a direct problem, represented by the line source distribution along the body long axis, whose strength is at the variation rate of the double cross-section areas of the body. The flow near the body is reduced to the two-dimensional flow problem of the deformation, vertical and lateral translations of double cylinders in a symmetrical manner. In particular, an analytical flow solution is obtained for a slender body of revolution at angles of attack and yaw, moving near an arbitrary curved ground. The attraction and side force, and pitching and yaw moments, acting on the body, are obtained in the form of the integrals along the body length by using the control volume method. Numerical analyses are then performed for the body moving near flat, convex, concave, and wavy grounds, respectively. The analyses reveal the orders of the attraction and side force, and pitching and yaw moments, as well as their variation trends in terms of the angles of attack and yaw of the body, the profile of the curved ground, and the clearance between them, etc. These irrotational dynamic features provide a basic understanding of the problem, which will be beneficial to further numerical and experimental studies involving more physical effects.
Dramatically improving polymer light-emitting diode performance by doping with inorganic salt
Authors: Zhao Wei , White J. M.
Published: August 2005

A simple method is described that dramatically lowers the turn-on voltage of polymer light-emitting diodes (PLEDs) by doping the electroluminescent polymer with an inorganic salt. Single-layer PLEDs were fabricated by spin-coating a solution of poly(9,9′-dioctylfluorene), doped with controlled amounts of LiBr, onto an indium tin oxide-coated glass (anode) followed by physical vapor deposition of an Al cathode. The turn-on voltage dropped from the undoped value of 7.4V as low as to 3.0V. These results are discussed in terms of alterations of the cathode-polymer and anode-polymer interfaces by Li+ and Br−.
Radial transport in magnetized non-neutral plasma driven by rotating wave
Authors: Kiwamoto Y. , Soga Y. , Aoki J.
Published: August 2005

Radial transport in non-neutral plasmas driven by a rotating wave field is examined in terms of the drift-kinetic Vlasov equation. It is shown that the radial flux is generated by the E×B drift of resonant particles subject to Landau damping in the axial dynamics. The rate of change in the canonical angular momentum associated with the radial flux is equal to the torque resonantly exerted by the azimuthal component Eθ of the wave. The absorbed wave energy is shared between the axial kinetic energy of the particles and potential energy of the charged particle system. The basic idea of this model may be extended to a scenario that the radial flux is generated by any other dissipative processes that shift the phase relation between the wave and the particle orbits.
Compositional symmetry breaking in ferroelectric bilayers
Authors: Zhong S. , Alpay S. P. , Mantese J. V.
Published: August 2005

Compositional variations across ferroelectric bilayers result in broken spatial inversion symmetry that can lead to asymmetric thermodynamic potentials. For the case of insulating materials, ferroelectric multilayers will self-pole due to the electrostatic coupling between the layers. Polarization-graded ferroelectrics with smooth composition, temperature, or stress gradients are viewed as bilayer structures in the limit of the ever-increasing number of bilayer couples, thus permitting us to conclude that the unconventional hysteresis associated with “up” and “down” polarization graded structures are real phenomena, and not artifacts associated with free charge or asymmetric leakage current.
Optical properties of Zn1−xCoxO thin films grown on Al2O3 (0001) substrates
Authors: Samanta K. , Bhattacharya P. , Katiyar R. S.
Published: August 2005

Thin films of Zn1−xCoxO (x=1–15%) were grown on an Al2O3 (0001) substrate by pulsed laser deposition and characterized by investigating their photoluminescence (PL) and other optical properties. The films were highly (0001) oriented without any impurity phases as observed in x-ray diffraction. The optical transmittance spectra showed that the band edge of Zn1−xCoxO was decreased with increase of Co concentration along with a subbandgap absorption in the range of 1.8to2.2eV. The near band-edge PL spectrum of ZnO thin films at 77K showed a strong peak of donor bound exciton at 3.307eV along with the free excitons. However, the PL spectra for free excitons of the Zn1−xCoxO films at 77K did not show any significant redshift due to Co incorporation.
Suppressing low-frequency noise in La0.8Ba0.2MnO3 films by a simple method of controlling film thickness
Authors: Touyama H. , Tanaka H. , Kawai T. , Kanai M.
Published: August 2005

Thin films of La0.8Ba0.2MnO3, whose temperature coefficients of resistance become high at around room temperature, were grown on SrTiO3(100) substrates by conventional pulsed-laser deposition, and the excess low-frequency electrical noise was measured in an ambient magnetic field. The two-probe noise spectra observed at room temperature can be described by the Hooge’s empirical relation. The Hooge parameter normalized by carrier density (γ∕n) was strongly dependent on the sample thickness, and films less than 50nm thick exhibited much lower noise than thicker films. This demonstrated dependence on thickness provides a simple and easy means of suppressing the noise in manganite thin films using conventional techniques.
Electrostatically actuated polymer microresonators
Authors: Zhang G. , Gaspar J. , Chu V. , Conde J. P.
Published: August 2005

Microresonators with a conductive polymer blend as the structural layer are fabricated using surface micromachining on glass substrates. A fabrication process using an aluminum sacrificial layer is developed that allows the preservation of the electrical conductivity of the polymer structural layer. The electromechanical properties of the all-polymer microbridges at high frequency are studied using electrostatic actuation and optical detection. The resonance frequency of the polymer bridges is in the MHz range and is affected by the tensile stress present in the structure. The Young’s modulus of the polymer structural material and the stress of the bridge are 3 GPa and 6 MPa, respectively. Quality factors are of the order of 100 in vacuum, decreasing with the measurement pressure for values above 1 Torr due to air damping.
Fundamental optical recombination in pentacene clusters and ultrathin films
Authors: He Rui , Tassi Nancy G. , Blanchet Graciela B. , Pinczuk Aron
Published: August 2005

Photoluminescence spectra of pentacene clusters and films of few monolayers in thickness reveal two fundamental excitations that are assigned to the Davydov doublets of the lowest singlet exciton. While the energy splittings of the doublets have minor dependence on cluster thickness, their bandwidths become narrower as the pentacene clusters grow larger and into continuous ultrathin films. The marked similarity of these Davydov doublets to those in optical absorption spectra of thicker pentacene films and crystals suggests a similarity in molecular arrangements. Luminescence of self-trapped excitons is quenched in the few monolayer clusters and ultrathin films.
Metalorganic chemical vapor deposition of lead-free ferroelectric BiFeO3 films for memory applications
Authors: Yang S. Y. , Zavaliche F. , Mohaddes-Ardabili L. , Vaithyanathan V. , Schlom D. G. , Lee Y. J. , Chu Y. H. , Cruz M. P. , Zhan Q. , Zhao T. , Ramesh R.
Published: August 2005

We have grown BiFeO3 thin films on SrRuO3∕SrTiO3 and SrRuO3∕SrTiO3∕Si using liquid delivery metalorganic chemical vapor deposition. Epitaxial BiFeO3 films were successfully prepared through the systematic control of the chemical reaction and deposition process. We found that the film composition and phase equilibrium are sensitive to the Bi:Fe ratio in the precursor. Fe-rich mixtures show the existence of α-Fe2O3, while Bi-rich mixtures show the presence of β-Bi2O3 as a second phase at the surface. In the optimized films, we were able to obtain an epitaxial single perovskite phase thin film. Electrical measurements using both quasistatic hysteresis and pulsed polarization measurements confirm the existence of ferroelectricity with a switched polarization of 110–120μC∕cm2, ΔP(=P*−P̂). Out-of plane piezoelectric (d33) measurements using an atomic force microscope yield a value of 50–60pm∕V.
Investigation of Ostwald ripening in nitrogen doped Czochralski silicon
Authors: Kissinger G. , Huber A. , Nakai K. , Lysytskij O. , Müller T. , Richter H. , von Ammon W.
Published: August 2005

Infrared laser scattering tomography was used to investigate Ostwald ripening in nitrogen-doped Czochralski silicon. Contrary to previous assumptions about oxide precipitation in nitrogen-doped silicon, the results clearly demonstrate that Ostwald ripening takes place during annealing of N-doped silicon wafers at 1000°C and 1100°C. The higher the nitrogen doping and the higher the temperature the faster the oxide precipitates grow and the faster they split into two fractions. One fraction is growing at the expense of the other.
Tuning of transmission peaks in two-dimensional semiconductor-based photonic crystals with line defects of cylinders
Authors: Manzanares-Martinez J. , Ramos-Mendieta F. , Halevi P.
Published: August 2005

We have studied transmission of light through two-dimensional photonic crystals of finite width, with the radii of the cylinders in the middle row altered in comparison to the host cylinders. Either the cylinder or the host material (for cylindrical holes) is a semiconductor, modeled by a realistic dielectric constant that takes into account free electrons, free holes, and lattice vibrations, as well as the dissipation related to each of these contributions. We considered both an intrinsic, narrow-gap semiconductor (InSb) and an extrinsic elemental semiconductor (Si). Our simulations of the transmission peak due to the line defects demonstrate that it can be substantially tuned by varying the temperature (for InSb) or the density of injected charge (for Si). The downside is absorption, which rapidly increases with temperature and impurity density. An optimized structure is suggested for experimental purposes.
Isovists, Enclosure, and Permeability Theory
Authors: Stamps Arthur E
Published: August 2005

Neurophysiological data and behavioral theory suggest that enclosure is a very important property of the environment. One technique for measuring enclosure is the mathematical construct of an isovist. An isovist is the set of points visible from a location. This paper reports analyses of 15 521 environments, ranging from cabin configurations in space stations to site plans for cities. Although results have been reported for twenty-five variables, it appears that only a few would be sufficient to distinguish between isovists. The most plausible variables are horizontal size and concavity. Judged enclosure was most strongly related to horizontal size, but it was also correlated with the variation in distance from the observation point to the isovist boundary, with boundary predictability, and with concavity. Numerical estimates of effect sizes are reported to assist in the efficient planning of future research.
How Ethnicity Influences Residential Distributions: An Agent-Based Simulation
Authors: Omer Itzhak
Published: August 2005

This paper deals with the influence of the organization of an agent's ethnic identities on ethnic residential patterns by extending the Schelling model to include a further hierarchical level; that is, the agents' ethnic identities are organized in a two-level hierarchy (each agent belongs to an ethnic group and subgroup). Agent-based simulation reveals that the residential pattern created at given levels of ethnic residential distribution can also be a response to intolerance behaviour at another level. The simulation experiments also show that these patterns can qualitatively change in response to different intensities of intolerance at both and/or either level. However, as a result of the asymmetric nesting of agents' ethnic identities and the tangible residential patterns subsequently established, top-down and bottom-up influences are generally displayed in the following form; intolerance behaviour at the top level strengthens the segregation observed at the bottom level whereas intolerance behaviour at the bottom level tends to weaken the segregation observed at the top level. This means that intolerance-motivated segregation between a minority and a majority in a city tends to strengthen segregation between ethnic subgroups within an ethnic minority community. Conversely, mutual intolerance between ethnic subgroups within an ethnic minority tends to moderate residential segregation between that minority community and the majority population. I suggest that these conclusions can be used empirically to evaluate the consequences of individual preferences for the ethnic composition characterizing residential patterns.
Black Holes in Galactic Nuclei, X-Ray Binaries and Ultraluminous X-Ray Sources
Authors: Kuncic Zdenka
Published: August 2005

This review summarizes the astrophysical evidence for the existence of black holes provided by their gravitational influence on nearby matter. Two classes of accreting black holes have now been observationally verified: supermassive black holes (SMBHs) in galactic nuclei, and stellar-mass black holes in X-ray binaries (XRBs). With the recent re-discovery of ultra-luminous X-ray (ULX) sources, fresh evidence has also emerged for the existence of a third class of accreting black holes: intermediate-mass black holes (IMBHs). The properties of the three classes of accreting black holes are briefly discussed.