bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship Between Longitudinal Coping Strategies and Outcomes in Patients With Acute Myeloid Leukemia
Authors: Amonoo Hermioni L. , Daskalakis Elizabeth , Deary Emma C. , Bodd Monica H. , Reynolds Matthew J. , Nelson Ashley M. , Newcomb Richard , Dhawale Tejaswini M. , Yang Daniel , Luger Selina M. , Gustin Jillian L. , Brunner Andrew , Fathi Amir T. , LeBlanc Thomas W. , El-Jawahri Areej
Published: October 2022

Background: Patients with acute myeloid leukemia (AML) face an abrupt life-threatening illness and experience immense physical and psychological symptoms. However, no data describe how patients with AML cope longitudinally with their illness or the relationship between longitudinal coping and outcomes. Methods: We conducted a secondary analysis of longitudinal data from 160 patients with high-risk AML enrolled in a supportive care intervention trial to describe coping strategies longitudinally across the illness course. We used the Brief COPE questionnaire, the Hospital Anxiety and Depression Scale, the Post-Traumatic Stress Disorder (PTSD) Checklist-Civilian Version, and the Functional Assessment of Cancer Therapy-Leukemia to measure coping strategies, psychological distress, and quality of life (QoL) at baseline and at weeks 2, 4, 12, and 24 after diagnosis. Electronic health records were used to assess healthcare utilization and end-of-life (EoL) outcomes, and multivariate analyses were used to assess the relationship between coping and outcomes. Results: Longitudinal utilization of approach-oriented coping strategies was significantly associated with less distress (anxiety: β, –0.18; P<.001; depression symptoms: β, –0.42; P<.001; PTSD symptoms: β, –0.60; P<.001) and better QoL (β, 2.00; P<.001). Longitudinal utilization of avoidant coping strategies was significantly associated with greater distress (anxiety: β, 0.64; depression symptoms: β, 0.54; PTSD symptoms: β, 2.13; P<.001 for all) and worse QoL (β, –4.27; P<.001). Although the use of approach-oriented and avoidant coping strategies was not significantly associated with hospitalization, chemotherapy administration, or hospice use in the last 30 days of life, approach-oriented coping was associated with lower odds of ICU admissions (odds ratio, 0.92; P=.049). Conclusions: Longitudinal use of approach-oriented coping strategies was associated with less psychological distress, better QoL, and a lower likelihood of ICU admission, suggesting a possible target for supportive oncology interventions. Coping strategies did not impact EoL outcomes, and further research is needed to elucidate which patient factors impact EoL decision-making.
Betydning af tilhør
Authors: Marschall Anja , Munck Crisstina
Published: October 2022

ResumeBetydning af børns tilhør i børnefællesskaber synes at være et underbelyst aspekt, når vi undersøger den gode opstart for børn i vuggestue. Vi analyserer i denne artikel, hvad pædagoger, forældre og børn oplever og forstår som en god opstart i vuggestuen, og hvordan det viser sig i praksis. Vi peger på, hvordan der med fordel kan bygges bro mellem forståelser af børns behov for tilknytning til voksne og børns behov for tilhør til børnefællesskaber. Artiklens analyser trækker på feltnoter og interviewmateriale med forældre, pædagoger og ledere i forskningsprojektet Samarbejde om småbørn (Marschall, Munck, Heinesen & Bæk, 2018-2020).
AbstractMeaning of belonging: Overlooked perspectives on children’s ”good” settling-in processes in ECECThe significance of children’s belonging to children’s communities seems to be an under-elucidated aspect when we examine the good settling-in processes for young children in ECEC. In this article, we analyze what pedagogues, parents and children experience and understand as a good “settling-in” in ECEC and how it appears in practice through their ways of taking part. We point to how understandings of children’s needs for attachment to adults can usefully be bridged by children’s needs for belonging to children’s communities. The analyses draw on field notes and interview material with parents, pedagogues and ECEC managers in the research project Collaboration about Toddlers (Marschall, Munck, Heinesen & Bæk, 2018-2020).
Ekspertkilder i landsdækkende danske dagblade
Authors: Johansen Kresten Roland , Johansen Jakob Dybro
Published: October 2022

Ekspertkilder optræder overalt i mediebilledet og bidrager til at give journalistikken autoritet og troværdighed. Men eksperterne udgør en broget forsamling og bruges i vidt forskellige roller og funktioner. Der mangler aktuel forskningsbaseret viden om, hvem de er, og hvad de bruges til. I denne artikel undersøges begge dele.

Vi laver en indholdsanalyse af fire ugers dækning i 2021 i de tre største landsdækkende dagblade: Jyllands-Posten, Politiken og Berlingske Tidende. Og sammenligner resultaterne med eksisterende forskning.

Knap halvdelen af dagbladenes ekspertkilder er privatansatte ikke-forskere. Økonomer og andre samfundsfagligt uddannede udgør 79 procent af disse. Blandt forskerkilderne udgør kvinder 22 procent. De er særligt underrepræsenterede inden for naturvidenskab. 86 procent af forskerkilderne udtaler sig om aktuelle begivenheder og andres forskning, mens 14 procent udtaler sig om egen forskning. I 98 procent af artiklerne med ekspertkilder castes en eller flere ekspertkilder til at levere vurderinger.

Resultaterne rejser spørgsmål om journalisters kriterier for at udvælge ekspertkilder, og om journalister tildeler ekspertkilder deres autoritetsfunktion på et tilstrækkeligt kildekritisk grundlag.
When a Robot Comes to Life
Authors: Pelikan Hannah , Broth Mathias , Keevallik Leelo
Published: October 2022

Conceptualizing agency is a long-standing theoretical concern. Taking an ethnomethodological and conversation analytic perspective, we explore agency as the oriented to capacity to produce situationally and sequentially relevant action. Drawing on video recordings of families interacting with the Cozmo toy robot, we present a multimodal analysis of a single episode featuring a variety of rapidly interchanging forms of robotic (non-)agency. We demonstrate how agency is ongoingly constituted in situated interaction between humans and a robot. Describing different ways in which the robot’s statuses as either an agent or an object are interactionally embodied into being, we distinguish “autonomous” agency, hybrid agency, ascribed agency, potential agency and non-agency.
Asymptotics of sums of divisor functions over sequences with restricted factorization structure
Authors:   División Matemática, Universidad Nacional de Luján, Jakimczuk Rafael , Lalín Matilde ,   Département de mathématiques et de statistique, Université de Montréal
Published: October 2022

We compute asymptotics of the sums of general divisor functions over h-free numbers, h-full numbers and other arithmetically interesting sets and conditions. The main tool for obtaining these results is Perron’s formula.
Mental Reality
Authors: Strawson Galen
Published: October 2022

What is distinctive of the mental? In Mental Reality, Galen Strawson argues that the answer is not intelligence, representational content, or intentionality broadly understood, but conscious experience. Strawson challenges neobehaviorist accounts of the mental. He argues that much contemporary philosophy of mind is still confused by positivism and its various offspring. It gives undue primacy of place to nonmental phenomena, publicly observable phenomena, and behavioral phenomena in its account of the nature of mind. Strawson describes an alternative position, naturalized Cartesianism, that couples the materialist view that mind is entirely natural and wholly physical with respect for the idea that the only distinctively mental phenomena are those of conscious experience.

Bradford Books imprint
Dynamic proteomic and phosphoproteomic atlas of corticostriatal axons in neurodevelopment
Authors: Dumrongprechachan Vasin , Salisbury Ryan B , Butler Lindsey , MacDonald Matthew L , Kozorovitskiy Yevgenia
Published: October 2022

Mammalian axonal development begins in embryonic stages and continues postnatally. After birth, axonal proteomic landscape changes rapidly, coordinated by transcription, protein turnover, and post-translational modifications. Comprehensive profiling of axonal proteomes across neurodevelopment is limited, with most studies lacking cell-type and neural circuit specificity, resulting in substantial information loss. We create a Cre-dependent APEX2 reporter mouse line and map cell-type-specific proteome of corticostriatal projections across postnatal development. We synthesize analysis frameworks to define temporal patterns of axonal proteome and phosphoproteome, identifying co-regulated proteins and phosphorylations associated with genetic risk for human brain disorders. We discover proline-directed kinases as major developmental regulators. APEX2 transgenic reporter proximity labeling offers flexible strategies for subcellular proteomics with cell type specificity in early neurodevelopment, a critical period for neuropsychiatric disease.
Automated mapping of Portulacaria afra canopies for restoration monitoring with convolutional neural networks and heterogeneous unmanned aerial vehicle imagery
Authors: Galuszynski Nicholas C. , Duker Robbert , Potts Alastair J. , Kattenborn Teja
Published: October 2022

Ecosystem restoration and reforestation often operate at large scales, whereas monitoring practices are usually limited to spatially restricted field measurements that are (i) time- and labour-intensive, and (ii) unable to accurately quantify restoration success over hundreds to thousands of hectares. Recent advances in remote sensing technologies paired with deep learning algorithms provide an unprecedented opportunity for monitoring changes in vegetation cover at spatial and temporal scales. Such data can feed directly into adaptive management practices and provide insights into restoration and regeneration dynamics. Here, we demonstrate that convolutional neural network (CNN) segmentation algorithms can accurately classify the canopy cover of Portulacaria afra Jacq. in imagery acquired using different models of unoccupied aerial vehicles (UAVs) and under variable light intensities. Portulacaria afra is the target species for the restoration of Albany Subtropical Thicket vegetation, endemic to South Africa, where canopy cover is challenging to measure due to the dense, tangled structure of this vegetation. The automated classification strategy presented here is widely transferable to restoration monitoring as its application does not require any knowledge of the CNN model or specialist training, and can be applied to imagery generated by a range of UAV models. This will reduce the sampling effort required to track restoration trajectories in space and time, contributing to more effective management of restoration sites, and promoting collaboration between scientists, practitioners and landowners.
New Chemical Dualities Illustrated by Meso and C2 Symmetrical (CTS) Compounds
Authors: Iga Dumitru Petru I.
Published: October 2022

The most important relationship between chemistry and genetics is nonetheless the corpuscular nature of their objects, molecules (or atoms) and genes, respectively. On the other hand, one states, without a substantial proof, that philosophy should be one step ahead all sciences. Here is a proof that the reverse can also be true. Two internal enantiomeric halves of meso compounds or the two chiral halves of ­C2 symmetrical isomers constitute pairs of entities suitable to work as duality phenomena in science. Four types of isomers have been identified: (A) meso, (B) C2 symmetrical (CTS), (C) irregular chiral (irrechi) and (D) constitutional (constit.). Meso and CTS are characteristic to plants and microorganisms. Almost all natural micromolecular compounds from vertebrate tissues are asymmetric, i.e. they are constit. isomers. An exception to this rule is meso-inositol, an isomer of hexoses, which are themselves, as their congeners asymmetric. By comparing the real (envisaged) meso isomers of these compounds with the asymmetric ones of vertebrate tissues, the reason for nature selected the latter became quite evident: it is the omission of a suite of structural restrictions. Delivering of meso isomers of natural compounds discloses a huge chemical philosophical potential of this issue. An intrinsic property of meso combinations is their character of dimerism, hence their molecule is formed of two entities that are contrary in a spatial, chemical and optical sense, i.e. good candidates for a duality concept. Moreover, a good deal of material is indicated, i.e. CTS isomers, whose sides are chiral and identical, for a new type of duality in philosophy, strongly expressed in nature by a chemical language.
Production of Fungal Pectin Lyase and Polygalacturonase from Fruit Wastes by Solid State Fermentation
Authors: Amande Tivkaa Joseph , Ado Benjamin Vandelun , Adebayo-Tayo Bukola Christianah
Published: October 2022

Polygalacturonase (PG or PGase) and Pectin lyase (PL) are depolymerase enzymes that split the α-1, 4-glycosidic linkages in the backbone of homogalacturonans. They are produced by microorganisms degrading pectin-containing substrates. PG and PL were produced in the solid-state fermentation (SSF) of beans testa (BT), mango peels (MP), Plantain peels (PP), and BT: MP: PP (1:1:1). Substrates were seeded with individual fungal strains namely Aspergillus tamarii, Aspergillus terreus, Aspergillus piperis, Aspergillus parasiticus and Mucor piriformis. PG production ranged from 0.0377 - 141.0095 U/g with A. tamarii, A. terreus and A. piperis producing the highest on mango peels. PL production ranged from 50.50 - 10,852.50 U/g with Mucor piriformis producing the highest on plantain peels. The pH of the fermentation medium changed during growth, metabolism, and pectinase production. The best pH for pectinase production falls within the acidic range. Unconventional substrates such as PP are viable for pectinase production, and PL yield in SSF is improved by compositing substrates.
Activation of rabbit blood platelets by anandamide through its cleavage into arachidonic acid
Authors: Braud Sandrine , Bon Cassian , Touqui Lhousseine , Mounier Carine
Published: July 2002

Anandamide (ANA), a cannabinoid receptor ligand, stimulated platelet aggregation at concentrations similar to those of arachidonic acid (AA). The aggregating effect of ANA was inhibited by aspirin but not by SR‐141716, a cannabinoid receptor antagonist. In addition, HU‐210, a cannabinoid receptor agonist, failed to induce platelet activation. Radiolabelling experiments showed that exogenous ANA was cleaved by platelets into AA through a phenylmethylsulfonyl fluoride (PMSF)‐sensitive pathway. In agreement, PMSF was shown to abolish the aggregating effect of ANA. In conclusion, ANA is able to induce platelet activation via its cleavage by a PMSF‐sensitive amidase activity, leading to the release of AA which in turn activates platelets.
Creatine kinase isoenzymes specificities: histidine 65 in human CK‐BB, a role in protein stability, not in catalysis
Authors: Mourad-Terzian Tamara , Steghens Jean-Paul , Min Kyung-Lyum , Collombel Christian , Bozon Dominique
Published: July 2002

Creatine kinases (CK) play a prominent role in cell energy distribution through an energy shuttle between mitochondria and other organelles. Human brain CK was cloned and overexpressed in COS‐7 cells. We then deleted His‐65 and/or Pro‐66 situated near the center of a flexible loop as shown by X‐ray crystallography on mitochondrial and cytosolic CK. The ΔH65 mutant had nearly the same affinity for its substrates as wild isoenzyme, but its stability was very low. Unlike ΔH65, ΔH65P66 had a eightfold decreased affinity for creatine phosphate and was unable to dephosphorylate cyclocreatine phosphate. Our results demonstrate that, despite an overall similar shape of the proteins, this loop accounts for some subtle differences in isoenzyme functions.
Titres of specific antibodies to poliovirus type 3 and tetanus toxoid in saliva and serum of children with recurrent upper respiratory tract infections
Authors: Cardinale Fabio , Gentile Vita , Brunetti Luigia , Hanson Lars Åke , Armenio Lucio
Published: July 2002

A study of antibody levels (in saliva and blood) against common vaccine antigens was performed in a population of 32 children suffering from recurrent upper respiratory tract infections (URTI). None of the patients had primary or secondary immunodeficiency syndromes or other known predisposing factors for respiratory diseases. Titres of the isotype‐specific antibodies immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin G (IgG) against two vaccine antigens – poliovirus type 3 (P3) and tetanus toxoid (TT), a viral antigen and a bacterial antigen, respectively – were measured in unstimulated saliva and serum, both in patients and in 24 healthy children (controls), by using a standard enzyme‐linked immunosorbent assay (ELISA). In addition, levels of total IgA and avidity of IgA antibodies to both P3 and TT in saliva were evaluated. No difference was found between patients and controls as to levels of total IgA, or specific IgA and IgM antibodies against both P3 and TT in saliva. Furthermore, the avidity of salivary IgA antibodies against the two antigens did not differ between the two populations. However, the average concentrations of saliva‐specific IgG antibodies to both the viral and the bacterial antigen were significantly lower (p < 0.01 for P3 and p < 0.05 for TT, respectively) in saliva of children with recurrent URTI, whereas no difference was found in serum for any immunoglobulin isotype determined compared with healthy individuals. The results of the present study provide suggestive evidence for the existence of subtle IgG‐restricted defects in antibody responses at the mucosal level, but not at the serum level, in some children with undue susceptibility to URTI.
Hypoallergenicity of an extensively hydrolyzed whey formula
Authors: Giampietro Paolo G. , Kjellman N. ‐I. Max , Oldaeus Göran , Wouters‐Wesseling Wendeline , Businco Luisa
Published: July 2002

Several different protein hydrolysate‐based infant formulas have been promoted as hypoallergenic and considered suitable for the dietary management of cow's milk allergy (CMA). Accepting that none of the hydrolysate‐based products is completely safe, the American Academy of Pediatrics (AAP) recommends that these formulas should be tested in a double‐blind placebo‐controlled setting and tolerated by at least 90% of children with proven CMA. In principle, this recommendation is also endorsed by the European Society of Paediatric Gastroenterology and Nutrition (ESPGAN) and the European Society of Paediatric Allergy and Clinical Immunology (ESPACI). In this two‐center study, 32 children with proven CMA were tested with the extensive hydrolysate whey formula Nutrilon Pepti, for comparison with Profylac (extensive) and Nan HA (partial) whey hydrolysate products. Skin‐prick tests (SPTs) were, respectively, positive to the three hydrolysate formulas in 19%, 15%, and 32% of children. After oral challenge it was concluded that 97% (95% CI: 85–100%) of the children tolerated Nutrilon Pepti, 94% (95% CI: 75–100%) tolerated Profylac, and 64% (95% CI: 37–81%) tolerated Nan HA. This study demonstrates that the extensive hydrolysates Nutrilon Pepti and Profylac are well tolerated in a population of children with proven CMA and that both products can be considered safe for their intended use. This study confirms that a very small number of children react even to extensively hydrolyzed formulas. SPT prior to oral exposure to the hydrolysate‐based formulas can indicate whether a child is at risk of showing reactions to the product. Introduction of new products to these children should be carried out under a doctor's supervision. However, the majority of the SPT‐positive children did tolerate the two extensively hydrolyzed whey‐based formulas tested.
Expression and purification of functional recombinant meningococcal transferrin-binding protein A
Authors: OAKHILL Jonathan S. , JOANNOU Christopher L. , BUCHANAN Susan K. , GORRINGE Andrew R. , EVANS Robert W.
Published: July 2002

Pathogenic bacteria of the genus Neisseria have a siderophore-independent iron-uptake system reliant on a direct interaction between the bacterial cell and human transferrin (hTf), a serum protein. In the meningococcus, this uptake system is dependent on two surface-exposed, transferrin-binding proteins (Tbps), TbpA and TbpB. TbpA is highly conserved among meningococcal strains, and is thought to be a porin-like integral protein that functions as a gated channel for the passage of iron into the periplasm. TbpB is more variable in size, lipidated and fully surface-exposed. Given its location on the cell surface, its role in pathogenicity and interstrain sequence conservation, TbpA is currently being regarded for inclusion in a meningococcal vaccine effective against all serogroups. This requires gaining knowledge of the ligand—receptor interactions. In the present study we have optimized a procedure for obtaining purified, functionally active recombinant TbpA at a level and stability necessary for the initiation of such studies.
Corticotropin increases protein tyrosine phosphatase activity by a cAMP‐dependent mechanism in rat adrenal gland
Authors: Paz Cristina , Cornejo Maciel Fabiana , Mendez Carlos , Podesta Ernesto J.
Published: July 2002

Corticotropin signal transduction pathway involves serine/threonine protein phosphorylation. Recent reports suggest that protein tyrosine dephosphorylation may also be an integral component of that pathway. The present study was performed to investigate the role played by protein tyrosine phosphatases (PTPs) on acute response to corticotropin and the hypothetical regulation of PTPs by this hormone. We have used two powerful cell permeant PTP inhibitors, phenylarsine oxide (PAO) and pervanadate (PV), in order to examine the relevance of PTP activity on hormone‐stimulated and 8‐bromo‐adenosine 3′,5′‐phosphate (8Br‐cAMP is a permeant analogue of adenosine 3′,5′‐phosphate)‐stimulated steroidogenesis in adrenal zona fasciculata (ZF) cells. In both cases, PAO and PV inhibited the steroid production in a dose‐dependent fashion, and had no effect on steroidogenesis supported by a permeant analogue of cholesterol. The effect of hormonal stimulation on PTP activity was analyzed in rat adrenal ZF. In vivo corticotropin treatment reduced phosphotyrosine content in endogenous proteins and produced a transient increase of PTP activity in the cytosolic fraction, reaching a maximum (twofold) after 15 min. Incubation of adrenal ZF with 8Br‐cAMP also produced PTP activation, suggesting that it can be mediated by cAMP‐dependent protein kinase (PKA)‐dependent phosphorylation. Detection of PTP activity in an in‐gel assay showed three corticotropin‐stimulated soluble PTPs with molecular masses of 115, 80 and 50 kDa. In summary, we report for the first time a hormone‐dependent PTP activation in a steroidogenic tissue and provide evidence that PTP activity plays an important role in corticotropin signal pathway, acting downstream of PKA activation and upstream of cholesterol transport across the mitochondrial membrane.
Epidemiological comparison of central and peripheral infective corneal infiltration: influence of contact lens wear and other risk factors
Authors: Seal D. , Devonshire P. , Hay J. , Kirkness C. , Bennett H.
Published: July 2002

Purpose: Risk factors for microbial keratitis (mk) are previous ocular surface, disease, contact lens (CL) wear and trauma. Their respective roles for central and peripheral infiltration (CI and PI) reflect changing primary car practice influencing predisposing causes. This study quantifies risk factors.

Methods: The study was conducted over nine months. All cases of putative mk were investigated using intensive culture of corneal scrapes. Risk factor data were recorded. All patients receiving antimicrobial therapy were included.

Results: 26/54 patients (48%) had CI (46% wore CL), 3/54 (6%) had paraxial infiltration and 25/54 (46%) had PI (40% wore CL). For CI, 14/26 (54%) yielded Acanthamoeba sp. (4), S. aureus (3), S. pneumoniae (3), S. viridans (1), Ps. aeruginosa (2) and Acinetobacter sp. (1); 8/14 (57%) wore CL [FDA groups 1(2), 2(1), 4(5)], the former 3 extended wear, the latter 5, 4‐weekly use of ‘disposable’ CL. 5 CI had ocular surface disease (4 HSV); 1 had trauma (mascara brush) with contaminated drops. For PI, 2/25 (8%) were cultured‐positive (1 S. aureus and 1 S. pneumoniae); neither wore CL and other recognized factors were absent.

Conclusions: Predisposing factors in culture‐positive CI were CL wear and previous HSV keratitis. Compliant use of hydrogen peroxide disinfection in CL wearers was not associated with culture‐positive infiltration.
An arabic letter distance visual acuity test chart for young children and illiterate adults
Authors: Oduntan A.O. , Briggs S.T.
Published: July 2002

This paper describes the design of a kinetic response Arabic letter distance visual acuity test chart for young children and illiterate adults.

An Arabic letterein which has previously been used in the design of Arabic alphabet VA charts was employed. Four different orientations of the letter were constructed on a 5×5 unit format and graded according to log MAR principle of acuity scaling using an Apple computer. Inter‐letter space in each row was made equal to the width of each letter in the row, and inter‐row space was made equal to the height of letters in the next lower row.

The chart has 14 acuity rows ranging from 4/40 to 4/2 (6/60 to 6/3) (20/200 to 20/10) (log MAR 1.0 to −0.3) at 4 metres.

To establish the validity of the chart, acuity values obtained using the chart were compared with those from an existing Arabic log MAR distance VA chart and the Bailey and Lovie distance VA chart. Test retest reliability of the chart was also examined statistically.

Results show that VA values from the new chart were significantly similar with those from which it was compared, and that values from the chart are reliable. The chart will be useful for evaluating vision, especially for young children and illiterate adults.
The characteristics of near prism induced fixation disparity curve in Hong Kong Chinese
Authors: Kwan Lawrence K.H. , Lam Andrew K.C. , Kwan Calvin K.F. , Yeung Pauline H.N.
Published: July 2002

The characteristics of prism induced fixation disparity curve at near were studied in 56 asymptomatic young adult Hong Kong Chinese (average age 21 years). The percentage distribution of types of fixation disparity curves was found to be similar to some previous studies, with a higher prevalence of Type I curve (64.3%), followed by Type II (28.6%) and Type III (7.1%) curves. No Type IV curve was revealed from the sample. Two modified measurement approaches were applied to study the effect of measurement techniques on the parameters of fixation disparity curve obtained. A thorough description of the techniques was given. Although a significant difference in thex‐ andy‐intercepts was obtained between different methods, the curve type and slope were not affected. The averagey‐intercepts (fixation disparity) were 2.72 min of arc and 3.54 min of arc from two methods respectively. Forty‐one subjects hadx‐intercept (associated phoria) found from the curve. The average values were 2.42Δ base‐out and 3.54Δ base‐out from two methods respectively.
Synchrotron radiation induced metal deposition on semiconductors: Mo(CO)6 on Si (111)
Authors: Zanoni R. , Piancastelli M. N. , McKinley J. , Margaritondo G.
Published: July 2002

We found that unmonochromatized soft x-ray synchrotron radiation stimulates the dissociation of molecular Mo(CO)6 adsorbed on silicon, producing a metallic overlayer. The process, which is interesting for potential applications, was studied using soft x-ray photoemission spectroscopy.
Cut-off characteristics of leaky Sezawa and pseudo-Sezawa wave modes for thin-film characterization
Authors: Kushibiki J. , Ishikawa T. , Chubachi N.
Published: July 2002

A new method of determining the elastic constants, density, and thickness of thin-film materials with the line-focus-beam acoustic microscope is developed using propagation characteristics of leaky Sezawa and pseudo-Sezawa waves in the neighborhood of the cut-off region. It is demonstrated for a sample of gold film on fused quartz that the values of the stiffness constant, C44, and density are, respectively, about 11% and 5.5% less than those for polycrystalline bulk gold, and the thickness is determined as 6370 Å.
Noncritical phase matching for guided-wave frequency conversion
Authors: Lim E. J. , Matsumoto S. , Fejer M. M.
Published: July 2002

Inhomogeneities in waveguide dimensions are a serious problem for guided-wave frequency conversion devices. We discuss waveguide designs that make the phase matching ‘‘noncritical’’ with respect to small changes in dimensions. Application of noncritical phase matching results in larger fabrication tolerances, facilitating the practical realization of nonlinear devices with long interaction lengths. We experimentally demonstrate the existence of a noncritical thickness in a lithium niobate waveguide, and analyze the dimensional tolerances for second-harmonic generation in a polymer waveguide.
Band offset of GaAs/In0.48Ga0.52P measured under hydrostatic pressure
Authors: Chen Jianhui , Sites J. R. , Spain I. L. , Hafich M. J. , Robinson G. Y.
Published: July 2002

Low-temperature photoluminescence spectra of an In0.48Ga0.52P alloy and a p-type GaAs/In0.48Ga0.52P multiple quantum well, both grown by molecular beam epitaxy, have been obtained under hydrostatic pressures from 0 to 6 GPa. The zero-pressure extrapolation of the InGaP(X) to GaAs(Γ) transitions yields a 0.40±0.02 valence-band offset, and hence only a small, 0.06 ± 0.02 eV, conduction-band offset. These offset values are in agreement with measured values of the confinement energy versus well width.
Novel contactless mode of electroreflectance
Authors: Yin X. , Pollak Fred H.
Published: July 2002

We report a new contactless mode of electroreflectance which utilizes a condenserlike system. One electrode consists of a transparent conductive coating on a transparent substrate which is separated from the sample surface by a thin layer of air. We have measured the contactless electroreflectance spectra at 300 K from a number of materials including semi-insulating bulk GaAs, bulk narrow gap Hg0.8Cd0.2Te, a GaAs structure with a large, uniform electric field and a GaAs/Ga1−xAlxAs (x≊0.2) coupled double quantum well.
Temperature dependence of long wavelength semiconductor lasers
Authors: O’Gorman J. , Levi A. F. J. , Tanbun-Ek T. , Coblentz D. L. , Logan R. A.
Published: July 2002

We compare the temperature dependent characteristics of multiple quantum well semiconductor laser diodes and light emitting diodes operating at a wavelength, λ=1.3 μm. No model in which Auger recombination is the dominant temperature sensitive parameter can explain our experimental observations. We suggest that net gain is the appropriate temperature dependent variable which determines laser diode performance at elevated temperatures.
Flux pinning by ordered oxygen-deficient phases in nearly stoichiometric YBa2Cu3O7−δ single crystals
Authors: Vargas João L. , Larbalestier David C.
Published: July 2002

We propose that the critical currents of nearly stoichiometric YBa2Cu3O7−δ single crystals (δ<0.1) are determined by fluxon pinning at ordered oxygen-vacancy domains. Since these domains are also superconducting, albeit with lower Tc and Hc than the stoichiometric matrix, their pinning strength at a given temperature will increase as they are driven normal by an increasing applied field. Experimentally, the magnetization hysteresis curves display a secondary maximum, characteristic of pinning by a superconducting second phase. The ordered-vacancy domains are assumed to result from a spinodal decomposition. The density and size of the domains were calculated on this assumption. The bulk pinning force was computed by direct summation. In the limit of low temperatures, the calculated values of critical current density Jc are in good agreement with measurements on high-quality single crystals.
Quantitative characterization of epitaxial superlattices by x-ray diffraction and high resolution electron microscopy
Authors: Fullerton Eric E. , Cao Wei , Thomas Gareth , Schuller Ivan K. , Carey Matthew J. , Berkowitz Ami E.
Published: July 2002

Quantitative x-ray diffraction (XRD) and high resolution electron microscopy (HREM) have been applied to the analysis of an epitaxial CoO/NiO superlattice. This example shows that the qualitative information determined directly from a XRD spectrum or HREM image is limited and can even be misleading. However, by a combination of quantitative intensity measurements and structural modeling, a detailed quantitative characterization of the superlattice structure is possible.
18O diffusion through amorphous SiO2 and cristobalite
Authors: Rodríguez-Viejo J. , Sibieude F. , Clavaguera-Mora M. T. , Monty C.
Published: July 2002

Secondary ion mass spectrometry was used to profile the diffusion of oxygen in polycrystalline β-cristobalite and vitreous SiO2. The tracer concentration profiles of cristobalite are consistent with a model based on two mechanisms: bulk and short-circuit diffusion. The profiles of partially crystallized samples containing vitreous SiO2 and β-cristobalite were fitted using the sum of two complementary error functions and taking account of some interstitial-network exchange. The bulk oxygen diffusivity, in the temperature range 1240–1500 °C, is about five times greater for vitreous silica than for β-cristobalite.
Coulomb blockade in the inversion layer of a Si metal-oxide-semiconductor field-effect transistor with a dual-gate structure
Authors: Matsuoka Hideyuki , Ichiguchi Tsuneo , Yoshimura Toshiyuki , Takeda Eiji
Published: July 2002

We have studied the transport properties of artificially squeezable inversion layers in a Si metal-oxide-semiconductor field-effect-transistor with a dual-gate structure. Increasing the potential barrier height with constant intervals along the one-dimensional channel gradually transforms a simple quantum wire into coupled quantum dots. The clear change in transport properties has been observed by changing the tunnel barrier height at low temperatures. The experimental results are discussed in terms of one-dimensional subbands and the Coulomb blockade of single-electron tunneling.
Growth of oriented diamond on single crystal of silicon carbide (0001)
Authors: Suzuki T. , Yagi M. , Shibuki K.
Published: July 2002

Diamond was deposited on a (0001) plane of an α-silicon carbide single crystal by the microwave method. The substrate surface was cleaned by pretreatment with hydrogen gas at 1200 °C. Cubo-octahedral diamond crystals with (111)D∥(0001)SiC were obtained.
Effects of wafer bow and warpage on the integrity of thin gate oxides
Authors: Thakur R. P. S. , Chhabra N. , Ditali A.
Published: July 2002

We have studied the effects of initial wafer bow and warpage on the integrity of thinner gate oxides grown by both furnace and rapid thermal processing (RTP) methods. There is evidence of a correlation between wafer warpage and bow to the charge-to-breakdown characteristics of the gate oxide. An almost linear increase in defect density was observed when plotted as a function of increasing wafer warpage. The lifetime (t50%) of the samples with initial warpage of 10 μm or less is reported higher than those with initial warpage of more than 60 μm for both furnace and RTP-grown oxides. The value of bow for the warped samples was taken for cases with the highest positive and negative values so both kinds of shape trends could be investigated. With initial wafer warpage ranging from 4 to 70 μm, we present the results of wafer dimensional analysis and correlate these to defect density and lifetime studies for thin gate oxides.
Influence of the finite lateral potential barriers on the optical spectra of quantum well wires
Authors: Benner S. , Haug H.
Published: July 2002

We calculate the plasma-density dependent optical absorption spectra of quantum well wires with finite lateral confinement with respect to the quantum well. The excitonic absorption spectrum consists of a series of resonances due to quantum wire as well as higher lying quantum well states. The calculations include phase-space filling, band-gap renormalization, and excitonic enhancement within the Hartree–Fock approximation. For a well depth of ≂40 meV, which is a typical value for intermixed GaAs/AlGaAs quantum well wires, the line shape of the quantum wire absorption spectrum is shown to be strongly influenced by the presence of lateral barrier states for all plasma densities.
New doped lithium niobate crystal with high resistance to photorefraction—LiNbO3:In
Authors: Kong Yongfa , Wen Jinke , Wang Huafu
Published: July 2002

Highly indium-doped lithium niobate crystals have been grown. It was found that a LiNbO3:In (5 mol %) crystal had a similar high resistance to photorefraction as a LiNbO3:Zn (7.5 mol %) crystal. The result of x-ray fluorescence showed that the doped concentration of In in LiNbO3:In (5 mol % in the melt) exceeds the concentration threshold of trivalant elements (3.0 mol % in the crystal). The LiNbO3:In (5 mol %) crystal is another doped LiNbO3 crystal with high resistance to light-induced refractive index damage.
Direct writing of Mo microstructures using high brilliance synchrotron radiation
Authors: Väterlein P. , Wüstenhagen V. , Umbach E.
Published: July 2002

Direct deposition of Mo microstructures on Si is demonstrated by photolytic decomposition of condensed Mo(CO)6 using the aperture-limited, high-intensity radiation from an undulator at the BESSY storage ring. A particular advantage of the instrument, a new photon-induced scanning Auger microscope, is the possibility of quasisimultaneous exposure (writing) and analysis employing photoemission (PES) or x-ray induced Auger spectroscopy (XAES) with sufficient energy resolution for detection of chemical differences. The present spatial resolution is 20–30 μm (for PES and writing) and 3 μm (for XAES), but this will be improved by adding focusing mirrors.
Measurements of rheological fluid properties with the falling needle viscometer
Authors: Park Noh A. , Irvine Thomas F.
Published: July 2002

The use of data from the falling needle viscometer to determine the rheological properties of purely viscous non-Newtonian fluids is described. From the solution of the basic flow equation, which is given in tabular and graphical form, a method is presented to determine rheological flow curves for both power law and more generalized rheological fluids. The use of the instrument to determine the zero shear rate viscosity is also described and a method of fitting appropriate constitutive equations to the data is discussed and illustrated by examples. Finally, a technique for measuring fluid densities using the falling needle viscometer is presented that is applicable to both Newtonian and power law fluids.
GaAsP spin-polarized electron source for a 300 keV accelerator
Authors: Mergl E. , Geisenhofer E. , Nakel W.
Published: July 2002

We report on a GaAsP spin polarized electron source designed to operate in high voltage terminals of electrostatic accelerators of several hundred kV. The small source of simple mechanical and electron-optical design can easily be connected to an accelerator tube. A stable beam of 35%–40% degree of polarization can be produced with a lifetime of several weeks. A measurement of the asymmetry in the emission of bremsstrahlung by transversely polarized electrons has been performed.
Loading system for alkali metal sources
Authors: Scheidemann Adi , Kresin Vitaly
Published: July 2002

A simple and very clean loading system for alkali metal sources is described. Ampules with pure sodium are opened inside a vacuum container and the metal is then transferred to the source reservoir.
The continuing development of low-energy electron microscopy for characterizing surfaces
Authors: Veneklasen Lee H.
Published: July 2002

Instrumental aspects of low-energy electron microscopy are reviewed with a view toward the future evolution of this reemergent technology. Both elastically scattered and inelastically excited electrons in the 0–1000-eV range may be used to form direct rather than scanned images of surfaces in the 3–10-nm resolution range. Different instrumental setups may be used to form images that selectively contain information about the topography, crystalline structure, chemical composition, or magnetic orientation of the first few monolayers. Frequently, parallel imaging allows observation of dynamic processes occurring during observation. Key electron optical elements and their systemic relationships are described in the context of a still hypothetical generalized instrument that would allow complementary exploitation of many contrast modes. Image quality issues such as resolution, sensitivity, statistics, and contrast selectivity are considered with a view toward their optimization, in many cases by drawing ideas and technologies from other fields of microscopy.
Hybrid BEEQ tandem mass spectrometer for the study of ion/surface collision processes
Authors: Winger B. E. , Laue H. -J. , Horning S. R. , Julian R. K. , Lammert S. A. , Riederer D. E. , Cooks R. G.
Published: July 2002

A hybrid mass spectrometer consisting of a magnetic sector, two electric sectors, and a quadrupole mass filter (BEEQ) has been built for the study of polyatomic ion/surface collision phenomena over the energy range of a few electron volts to several keV. Primary ions are generated by electron ionization or by chemical ionization, and the first two sectors are used to deliver a monoenergetic beam of ions, of a selected mass-to-charge m/z ratio, to a decelerator which sets the desired collision energy. The target, which can be introduced into the system without breaking vacuum, is mounted on a goniometer and situated in an electrically shielded region in the center of a large scattering chamber which contains an electric sector and a quadrupole mass analyzer used for kinetic energy and mass measurements on the ejected ions. These analyzers rotate around the scattering center to allow selection of the scattering angle of ions leaving the surface.

Ultimate pressures attainable in the main scattering chamber are below 10−9 Torr allowing molecular targets, such as self-assembled monolayers of alkyl thiols on gold, to be examined without surface contamination. Low-energy (20–100 eV) collisions of polyatomic ions are reported, and examples are given of the effects of collision energy and scattering angle on surface induced dissociation mass spectra. The kinetic energy of the inelastically scattered ions is also measured, and in some cases, the internal energy can be estimated, the two measurements together providing information on energy partitioning associated with surface collisions. For example, it is shown that n-butylbenzene molecular ions of 25 eV colliding with ferrocenyl-terminated self-assembled monolayer surfaces, rebound with 10 eV of recoil energy and 3 eV of internal energy.

The remainder of the energy goes into the surface. The capability of the BEEQ instrument to provide data on ion/surface reactive collisions is also illustrated with reactions such as alkyl group transfer at self-assembled monolayer surfaces. In addition, data are given showing the ability of the system to provide information on the kinetic energy distributions of ions generated in the course of high-energy collisions at the surface. Mass analysis of the sputtered products provides the instrument with secondary-ion mass spectrometry capabilities.
High contrast computed tomography with synchrotron radiation
Authors: Itai Yuji , Takeda Tohoru , Akatsuka Takao , Maeda Tomokazu , Hyodo Kazuyuki , Uchida Akira , Yuasa Tetsuya , Kazama Masahiro , Wu Jin , Ando Masami
Published: July 2002

This article describes a new monochromatic x-ray CT system using synchrotron radiation with applications in biomedical diagnosis which is currently under development. The system is designed to provide clear images and to detect contrast materials at low concentration for the quantitative functional evaluation of organs in correspondence with their anatomical structures. In this system, with x-ray energy changing from 30 to 52 keV, images can be obtained to detect various contrast materials (iodine, barium, and gadolinium), and K-edge energy subtraction is applied. Herein, the features of the new system designed to enhance the advantages of SR are reported. With the introduction of a double-crystal monochromator, the high-order x-ray contamination is eliminated. The newly designed CCD detector with a wide dynamic range of 60 000:1 has a spatial resolution of 200 μm. The resulting image quality, which is expected to show improved contrast and spatial resolution, is currently under investigation.
A Penning trap mass spectrometer for the study of cluster ions
Authors: Becker St. , Dasgupta K. , Dietrich G. , Kluge H.-J. , Kuznetsov S. , Lindinger M. , Lützenkirchen K. , Schweikhard L. , Ziegler J.
Published: July 2002

A Penning trap system has been set up for storing and investigating cluster ions over time ranges from microseconds up to minutes. This enables studies of cluster reactions with extremely low cross sections and the observation of their time dependence in a new regime. The ions are created externally by laser vaporization, cooled by adiabatic expansion of a supersonic beam, and injected into the Penning trap. Detection of reaction products is achieved by combining the advantages of two complementary approaches, viz. the high resolution of Fourier transform mass spectrometry and the high sensitivity of single-ion counting with a time-of-flight mass spectrometer. The performance of the apparatus is illustrated by results of recent cluster experiments.
Optical mapping of fluid density interfaces: Concepts and implementations
Authors: Zhang X. , Dabiri D. , Gharib M.
Published: July 2002

Several ideas of color encoding for surface slope measurements are systematically explored and reviewed to develop a new set of fundamental concepts. It is shown that different systems, such as shadowgraphs, Schlieren optics, and our water surface gradient detectors, can also be universally described through the concepts of sun glitter functions, incident light-source encoding, and observer encoding. These concepts provide a more precise way of mathematically formulating and physically interpreting the flow visualization images, thereby providing quantitative results. It is this new system of concepts that uncover the quantitative potential of these optical methods. The measurement abilities of various existing optical systems are thus enhanced from qualitative observation or visualization to the well-defined quantitative measurement. This is a critical step forward. The concepts can also be further extended to measure fluid flows with multiple density layers or flows with continuous density variations. As an example of implementation, the method of measuring a water-surface gradient is extended into a reflective approach of detecting small changes of surface slope at an air–water interface. In this process, fluid surface slopes (surface gradients) are first optically mapped into color space. An array of lenses is used to transform the rays of an optical light source into a series of colored parallel light beams by passing the light through a group of two-dimensional color palettes at the focal planes of the lens array. This system of parallel light beams is used to illuminate a free surface of water. The reflected rays from the free surface are captured by a charge-coupled device color camera located above the surface. The slopes are derived from the color images after the calibration, and surface elevations are obtained by integrating the slopes. This technique is then applied to observe free-surface deformations caused by near-surface turbulence interacting with the free surface.